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OCR for page 49
Production and
Maintenance
The manufacture of modern jet transport aircraft is an
organizational tour-de-force. Components of the air-
craft--wings, tail and landing gear assemblies, fuselage
sections, doors and latches, avionic and radio equip-
ment--arrive at the assembly plant from all over the
world. In hangars the size of several football fields,
work crews tow the airplanes through a dozen or more
positions on the production line, until each finished
airplane eases from the hangar ready for testing and ap-
proval for flights.
Once an airplane is in service, the airline performs
myriad maintenance operations on it--daily checks, peri-
odically scheduled maintenance, major overhauls, repairs
of unexpected damage and replacement of failed compo-
nents. The number of aircraft in daily service for each
air carrier, the complexity of the airplane, the distan-
ces between centers of operations, and the variations in
procedures and practices among airlines all figure into
a maze of maintenance operations in which millions of
actions are performed by thousands of individuals.
As a consequence, there are many opportunities for
assuring that each aircraft is built and maintained to
established safety standards. With careful workmanship,
failures are preventable. By alert examination, errors
are detectable. Carelessness and inattention, by con-
trast, often lead to mistakes and mishaps.
49
OCR for page 50
IMPROVING AIRCRAFT SAFETY/50
Quality Assurance in Production
For each new type of aircraft, a manufacturer must
obtain a Production Certificate from the FAA. Prior to
awarding the certificate, a team of specialists from the
FAA regional office, constituted as a Production Certi-
fication Board, reviews and evaluates the applicant's
proposed manufacturing and quality control procedures.
The review is intended to make sure that each aircraft
produced conforms to the design specifications of the
Type Certificate. Once the Production Certificate is
awarded, government oversight of production is main-
tained by a system that couples direct FAA review by
assigned inspectors with the work of delegated company-
employed Designated Manufacturing Inspection Representa-
tives (DMIRs).
The job of assuring that the aircraft meets the
design specification rests with the manufacturer's qual-
ity control organization. It reviews all aspects of the
production process, including the materials, parts,
tools, and equipment; the methods of operations and the
sequence in which these are performed; in-process and
final inspections and tests; and the qualifications and
training of all production personnel.
Inspections are performed by company employees who
are required to verify by formal record that the product
meets the established standards. The record signifies
that the inspector stands behind the proper performance
of the work. Articles are tagged or stamped with marks
that identify the individual inspector and ensure that
only inspected and accepted items are used in the fin-
ished product. For example, suitable "acceptance,"
"rework," or "rejection" stamps are placed on articles
subjected to heat-treatment, welding, riveting, solder-
ing, hardness tests, laboratory analysis, and other
tests.
Responsibility for the continuous review and moni-
toring of the quality control system on a daily basis
resides with the FAA Principal Inspector assigned to the
facility. The inspector supervises the work of and is
assisted by a staff of FAA inspectors and the Designated
Manufacturing Inspection Representatives. The designees
certify on behalf of the FAA that aircraft are consis-
tent with the approved design and specifications. FAA
inspectors provide surveillance of the entire production
OCR for page 51
51/Production and Maintenance
and quality control system. They also participate in
FAA enforcement actions, a function specifically exclud-
ed from the designee's authority.
Designees are company employees with many years'
experience in manufacturing or special processes and in
inspection, all gained with the same firm, generally.
They are nominated by the company and approved by the
FAA in a manner analogous to the appointment for design
review of the Designated Engineering Representatives.
Their responsibilities include: (i) the witnessing
and verification of tests; (ii) issuance of Aitrworthi-
ness Certificates (a certificate that the individual
aircraft meets the design specifications of the Type
Certificate and has been flown, either by FAA or company
test pilots on behalf of the FAA, and has been found in
compliance with applicable standards) and export approv-
als; and (iii) performance of conformity inspections.
In the last instance, they provide a second assurance
that the product conforms to its design, not by repeat-
ing the work of the company inspector, but by performing
an audit of what was done to the product. They also
work on behalf of the FAA during type certification to
determine whether or not prototype articles conform to
design data. Designees accomplish the audit primarily
by reviewing the paperwork and process documents. They
also make spot checks of the inspections at selected
points. Once an error is detected by a designee, he is
charged with seeing that it is corrected, but not neces-
sarily with reporting the error to the FAA.
The FAA inspector is charged with the broader re-
sponsibility of ensuring that the entire quality control
system is carried out in accordance with the plan sub-
mitted to the FAA and approved by its Production Certi-
fication Board--a procedure called "Certificate Manage-
ment." The FAA inspector's concern extends to the tools
or equipment used, the sequence of operations, the
training of the individual performing the work, and the
steps taken by the company's quality control organiza-
tion.
The processes that go into producing aircraft have
increased in number and complexity over the years. At
present, according to company representatives, quality
control activities represent approximately 15 percent of
the total cost of an aircraft. To verify that the mul-
tiple tasks are consistent with established procedures,
.
OCR for page 52
IMPROVING AIRCRAFT SAFETY/5 2
even oy reviewing the system on a spot check basis, is
beyond the daily capabilities of the few FAA inspectors
and manufacturing designees who work in production. For
instance, early in 1980, the FAA indicated that there
were only about 21 inspectors and 36 manufacturing
designees working in the production facilities of the
three major manufacturers. Most of the FAA staff had
other assignments.
Accordingly, the routine surveillance of the manu-
facturers' production and quality assurance systems by
FAA inspectors is augmented by special FAA teams who
periodically perform a Quality Assurance Systems Analy-
sis Review (QASAR) of the systems. Such in-depth audits
involve, primarily, a detailed examination of documents
and records. Little specific attention is given to
hardware.
The committee found the relationship between the FAA
principal inspectors and company designees to be one of
mutual respect.
_ _ _ , ~ _ _ ,
In comparing the two groups, it con-
cluded that the basic minimum requirements for training
and inspection experience were similar. Accumulated ex-
perience levels are about the same, as are basic salary
ranges, although the FAA offers a higher maximum salary
to its most senior inspectors.20
al actions only for the FAA.
Some differences exist among companies in how the
designees are used. At two companies, they are assigned
to the quality assurance organization, report to the FAA
Principal inspector, and Perform inspections and approv
At the third company, the
same functions are performed, although some functions in
addition to their FAA tasks are required at the direc-
tion of their employer.
The FAA regional office staffs view the work of the
designees as essential and of excellent quality. Simi-
larly, each of the companies describes the designee
function as necessary to demonstrating compliance with
the regulations. The committee is satisfied that FAA
manufacturing inspectors relate to their counterparts
essentially on a peer basis. The committee also found
that the team approach to auditing quality assurance is
well conceived, but that the typical intervals between
audit visits are too long, often as much as three years.
While the manufacturers' quality control systems and
the quality of the FAA inspectors appear generally to be
OCR for page 53
53/Production and Maintenance
good, there have been nevertheless a number of lapses
that raise warning flags. Examples are such production
failures as the faulty cargo door latch that caused the
Turkish Airlines DC-10 accident outside Paris21 and
the discovery in the course of an inspection, after the
Chicago accident of loose, failed, and missing pylon
spar web fasteners on another aircraft.22 Materials
used in aircraft production also may present quality
problems. In the absence of extremely alert quality
control PerSonnel' flaws can enter the manufacturing
cycle before they are identified.
In connection with the need for alertness, the com-
mittee observed that the FAA inspection personnel are
tied to their offices too much. It would be more valu-
able if inspectors were to establish their presence on
the production floor with greater frequency, observing
first-hand the manufacturer's fabrication and inspection
activities. While recognizing that it is not the FAA's
function to inspect and approve specific hardware and
operations, as the company inspectors must do, it is the
committee's view that an understanding of and judgments
about the total process are enhanced by greater famili-
arity with the hardware being produced, by observing the
manufacturing and inspection operations, and by talking
with the individuals performing the work.
Considering all of these matters, the committee
recommends that the FAA increase its emphasis on quality
ossuronoe in aZZ phoses of the production process by in-
oreasing the frequency of Quality Assurance Systems
Analysis and Review team visits to aZZ Production Certi-
ficote holders, and by expanding the responsibilities of
FAA inspectors and quality ossuranoe teams to inoZude
the observation of aotuaZ hardcore.
Maintenance Surveillance
Once a new aircraft leaves the manufacturerls plant
for use in service by a carrier, the responsibility for
maintaining it in compliance with applicable FAA regula-
tions devolves upon the airline. At the same time, the
day-to-day FAA responsibility shifts from the manufac-
turing review staff of the regional office to air carri-
er inspectors in the respective district offices, locat-
ed near the principal airports of the country.
OCR for page 54
IMPROVING A I RCRAFT SAFETY/ 5 4
Prior to operating a particular aircraft in revenue
service, the individual air carrier has to develop and
submit a maintenance program to its assigned FAA Princi-
pal Maintenance Inspector for approval. The program in-
cludes a combination of maintenance operations specifi-
cations and a manual of instructions for accomplishing
maintenance and inspection, as well as a means for their
administration. In practice, preparation of the initial
maintenance program for a specific type of aircraft is
begun early in the design stage. The FAA review is ac-
complished during the type and production certification
period. An industry committee, called the Maintenance
Steering Group (MSG), representing relevant airlines,
other operators who expect to purchase the airplane, and
the manufacturer, provides advice during its preparation.
Once the manufacturer has presented the initial mainte-
nance program and manual for approval to the FAA, the
document is reviewed in the regional office by a Mainte-
nance Review Board (MRB). The Board, an FAA committee
of specialists, including engineers and representative
maintenance and avionics inspectors, prepares a Mainte-
nance Review Board Report to approve the maintenance
program.
In the normal course of events, each carrier modi-
fies the initial maintenance program, subject to review
and approval by the FAA's assigned maintenance or avion-
ics inspectors, in light of the carrier's particular
maintenance practices and the experience gained from
maintaining the aircraft in service. The maintenance
program is also changed in response to Airworthiness
Directives (FAA regulations prescribing mandatory inspec-
tion and/or repair), manufacturers' service bulletins,
and relevant maintenance reports of other carriers
The process of revising both the manufacturer's
maintenance manual and the program in actual use by the
carriers is one of considerable magnitude. A major car-
rier visited by the committee includes in its mainte-
nance manual all engineering and maintenance policies,
procedures, specifications, and job instructions. Its
manual has 200,000 pages, in which some 300,000 pages of
revisions--some revised several times--were made during
one year.23
It is likely that two airplanes produced one after
the other on the same production line will be subject,
after a period of use by different carriers, to quite
OCR for page 55
55/Production and Maintenance
different maintenance operations. The particular route
and operation of each airline call for differences in
the type and frequency of the work required. Even so,
each carrier's program of maintenance bears the approval
of the FAA.
The FAA's primary means for effecting the surveil-
lance of the carriers' maintenance program is the as-
signment of Principal Maintenance (and Avionics) Inspec-
tors and their staffs at locations adjacent to the car
~ These officials are
responsible for assuring that the carriers to which they
are assigned maintain the airplanes in compliance with
the regulations. They do so primarily by reviewing the
airline's maintenance system and checking its mainte-
nance job records. Depending upon the workload and in-
clination of the respective inspectors, they may review
or spot-check actual work done or in progress.
This system of surveillance is supported by three
back-up activities: (i) FAA inspectors at other airport
facilities along the carrier's route perform ramp checks
to evaluate the apparent condition and routine servicing
of the aircraft; (ii) audit-type inspections, called
situation monitorings--analogous to the system of audits
performed for manufacturing by quality assurance teams,
though not so regular--are conducted in limited cases,
especially where the regional office becomes aware of
specific safety problems; and, (iii) a formal system for
reporting and reviewing accidents, incidents, and ser-
vice difficulties.
Boeing, Douglas, and Lockheed all have product
support departments that play important roles in their
respective operations. One has 1,440 product support
nersonnel;24 another has an even larger staff. These
units monitor the use of their products and provide as-
sistance to the owners, no matter how often the equip-
ment changes hands, because, as they view it, the per-
formance of one aircraft reflects on all others from a
manufacturer. Typically, company representatives are
assigned to an airline 30 days in advance of the de-
livery of a new type of aircraft. They assist the cus-
tomer, on request, with engineering and maintenance ad-
vice, provide specialized training as the need arises,
and, in general, become the carrier's instant point of
contact with the manufacturer. The company representa-
tives also gather and report home to their companies all
racers' principal maintenance bases.
OCR for page 56
IMPROVING AI RCRAFT SAFETY/5 6
data on component repair, routine operational data, and
other matters of technical significance.
Manufacturers regularly issue service bulletins to
their customers concerning recommendations related to
product improvement or reliability. One kind, called an
Alert Service Bulletin, which also is sent routinely by
the manufacturer to its FAA regional office, concerns
significant problems in which safety is considered an
issue. While many airlines may make changes immediately
in response to an Alert Service Bulletin, they are not
legally required to do so unless the PAA incorporates
the bulletin into an Airworthiness Directive (AD).
Carriers also are not required to report the completion
of work in response to service bulletins to either the
FAA or the manufacturer.
Service bulletins may or may not be reviewed by the
FAA maintenance inspector as part of the examination of
the airline's maintenance documents. However, the pro-
ject engineer in the regional office often considers the
Alert Bulletins for possible issuance of a mandatory
Airworthiness Directive.
. . .
The differences in maintenance organizations and
practices lead the FAA, in turn,
terpretations of the regulations _
inspectors. The lack of consistency from one office to
another is an inevitable and reasonable consequence of
the diversity of users' needs and not a shortcoming to
be eliminated.
There are, however, wide differences in the prac-
tices of FAA inspectors, especially the frequency of
their direct observation of the aircraft, the level of
their maintenance inspection activity, and their general
assertiveness. While the regulations make inspectors
responsible for approving the maintenance program and
any changes in it, the committee sees the system as
allowing and even encouraging them to view their res-
ponsibility as a passive one. Because of the importance
of maintenance to the safe operation of aircraft, the
FAA needs to do all it can to encourage its inspectors
to be more assertive, and to take full advantage of the
opportunities to detect and correct conditions they con-
sider to be unacceptable. As in the case of manufac-
turing inspectors, the committee found that, while FAA
maintenance inspectors now acquire information princi-
pally by reviewing documents, it is important that the
-
to varying local in-
bY its air carrier
OCR for page 57
57/Production and Maintenance
inspectors acquire first-hand familiarity with the
carriers' extensive maintenance activities that go on
around the clock.
One way of enabling inspectors to observe mainte-
nance events is to provide them with better tools and
knowledge about their work--e.g., access to carriers'
service computers and to their own computer systems,
more and better training about new aircraft, and annual
conferences on matters of wide concern. Periodic tele-
phone conferences linking inspectors to each other and
to regional project engineers would provide greater
understanding of the findings of other inspectors and
the possible implications of those findings.
FAA inspectors also should be encouraged to observe
more strategically, acting, for instance, on the natural
"cues" that the system provides. Cues are to be found
in Airworthiness Directives, individual aircraft main-
tenance records, manufacturers' service bulletins, gov-
ernment and industry trend analyses, and statistical
data. The manufacturer's issuance of an Alert Service
Bulletin, for instance, provides an opportunity for the
FAA inspector to gain insights on how the carrier per-
ceives a particular safety problem.
While there is a clear value to be gained by in-
creasing the awareness of the maintenance and avionics
inspectors to ongoing maintenance activities, as well as
their knowledge of other operations, the total amount of
activity and information generated will nonetheless ex-
ceed their day-to-day grasp and capabilities. Their
reach could be extended by reinstituting the systematic
deployment of the FAA's former Systemworthiness Aircraft
Program (SWAP) maintenance auditing teams to supplement
the work of the assigned inspectors. This program was
"reoriented" recently to the less regular "situation
monitoring" inspections,25 which are conducted in res-
ponse to known problem conditions.
With proper preparation, members of the reinstituted
teams could provide checks of the carriers' maintenance
systems from broadly based experience. They could be
specifically prepared to investigate individual areas of
concern prompted by analyses of reported problems, and
could be in a position to conduct spot reviews of air-
craft hardware to assure that Airworthiness Directives
are implemented and that other changes are made to safe-
guard the condition of the aircraft. By not giving
OCR for page 58
IMPROVING AI RCRAFT SAFETY/5 8
advance notification of an audit, the team could obtain
a candid picture of the actual circumstances of the op-
erator's maintenance program. Such team visits would
have an additional advantage of assuring that the per-
formance of the resident FAA inspection staff lives up
to expectations.
Because of the importance of maintenance to the
continued airworthiness of the carriers' aircraft, the
committee recommends that the FAA inoreose its surveiZ-
Zanoe of airline mointenonoe operations, making use of
team approach for frequent and unannounced inspections,
and encouraging its air carrier inspectors to give high-
er priority to strategioaZZy selected on-site visits and
hardware observation, both random by during aZZ shifts,
and for specific maintenance procedures that they deem
espeoiaZZy oritioaZ or important.
Licensing of Maintenance Personnel
With the exception of the flight crew, no group has
a greater effect on aircraft safety than the maintenance
workers at the airlines. It stands to reason that the
skill levels of mechanics and inspectors should be of
high quality and appropriate to the type and complexity
of the particular aircraft on which they are working.
The FAA certificates aircraft mechanics by awarding
Airframe and Powerplant (A&P) licenses after an indivi-
dual has passed written tests covering the construction
and maintenance of aircraft appropriate to the rating
sought.26 The FAA requires that all maintenance work
be signed off by an individual holding an appropriate
license. Under the present arrangement, an individual
obtains such ratings and remains perpetually licensed,
irrespective of the extent or kind of subsequent work
experience, training, or qualifications.
The development of increasingly complex, modern jet
transport over the past 30 years has led to rapid chang-
es in the level of skills and knowledge necessary to
maintain aircraft in airworthy condition. When the con-
cept of licensing or certificating U.S. airline mainte-
nance personnel was originally developed in the late
1920's, the aircraft and the air transportation system
OCR for page 59
59/Production and Maintenance
were far simpler. That was a period in which materials
and structures were less complex and reciprocating in-
ternal combustion engines and simple electric circuits
were the most important items affecting airworthiness.
The term "avionics," which combines modern aircraft
electrical, electronic, navigation and communication
systems, had not been coined. Today's maintenance staff
is required to bring great competence to aircraft func-
tions requiring avionics skills in operation and flight
control systems, protection and warning systems, commun-
ication and navigation components, instrumentation and
cockpit displays, and passenger support and safety
equipment. Such maintenance functions require knowledge
of complex equipment and circuits, and complex test
equipment. However, mechanics dealing with avionics do
not have special credentials under the present system.
By regulation, responsibility for the adequate
training of maintenance personnel lies with the car-
rier. It must provide "a training program to ensure
that each person who determines the adequacy of work
done is fully informed about procedures and techniques
and new equipment in use and is competent to perform his
duties. 27 In the committee's judgment, the FAA's
current licensing and training requirements for airline
maintenance personnel are, unhappily, of limited effec-
tiveness.
There is no stringent standard, comparable, for
instance, to that for flight crews, for initially estab-
lishing or periodically upgrading the skills of mechan-
ics who repair or service commercial aircraft. In 1977,
the FAA proposed an amendment to the regulation cited
above, observing that "no minimum standard exists today
to ensure that airline maintenance personnel have ade-
quate initial and recurrent training."28 This is still
the case. The change proposed in 1977 (but not yet
adopted) addressed only the requirement of certifica-
tion and training for supervisory personnel--i.e., the
persons who determine the adequacy of work perform-
ed.29 At present, there is no regulation that effec-
tively prevents an airline from assigning persons with
little relevant training and/or qualification to the
performance of critical maintenance tasks, as long as
someone who is certificated signs off the work. (The
committee has made no evaluation to determine if such
assignments are actually made in practice.) -
OCR for page 62
IMPROVING AIRCRAFT SAFETY/6 2
operation is the ultimate test. Accordingly, it is
largely through knowledge gained in operational experi-
ence that changes in maintenance procedures, and modifi-
cations to design, are made.
The manufacturer's experience in analyzing mainten-
ance operations and manufacturing changes is not always
sought, however, before maintenance programs or designs
are modified . While the designer participates directly
in the preparation of the initial maintenance program,
once the carrier begins to alter it, the FAA does not
require that the manufacturer holding the Type Certifi-
cate be consulted before changes are made. Further, the
FAA personnel or offices responsible for approving such
changes are not necessarily those who originally approved
the maintenance procedures during the certification of
the aircraft.
It is possible that some changes or modifications
will degrade the safety of the airplane in subtle ways
that only the aircraft designer is likely to discern.
Aircraft safety may be eroded by unusual procedures for
removing and reattaching major components, different
aircraft jacking or towing conditions, or changes in
liquids and gases used for servicing, purging, or clean-
ing. The modification of a fuselage to accommodate a
larger cargo loading door could result in changes to
load paths and the consequent overloading of another
critical part of the fuselage structure. In some cases,
the manufacturer will have more detailed knowledge than
the carrier about the strength of structures and sensi-
tivity to damage of the aircraft and its major compo-
nents. A requirement for seeking formal review by the
manufacturer, as well as the FAA, of a proposed signifi-
cant modification or variation in maintenance procedure
could improve the likelihood of early warnings of any
dangers.
In some cases, particularly as an aircraft puts on
many flight hours in operation and major component re-
placements are necessary, or as an airplane is modifi-
ed, the air carriers purchase parts and assemblies from
vendors other than the original manufacturer and either
make their own alterations or have the work done at a
Designated Alteration Station (DAS), a repair facility
whose work procedures have been approved by a regional
office of the FAA. In either case, the operator must
have received a Supplemental Type Certificate (STC) from
OCR for page 63
63/Production and Maintenance
the FAA prior to making the change. The application for
a certificate is handled by the regional office where
the carrier or repair facility is located, which, in
most instances, is not the same office that deals with
the manufacturer.
Just as with variations to the maintenance program,
changes can be introduced and even approved by a desig-
nee (subject to subsequent FAA approval) in cases where
the manufacturer-designer is best able to judge whether
or not unacceptable degradation to safety margins might
result. In this case, the designee could be a Consul-
tant Designated Engineering Representative, and not an
experienced employee of the original manufacturer.
Because the committee did not examine the matter of
consultant designees, it cannot extend its previous
favorable recommendation to anyone other than designees
employed by an aircraft maker.
With such considerations in mind, the committee
recommends that the FAA assure that the manufacturer
(type Certificate holder) have Continuing knowledge of
an operator's mointenonoe procedures by obtaining the
monufaoturer's formoZ review prior to authorizing any
significant deviation from the approved mointenanoe
program. SimiZorZy, it recommends that the FAA assure
that the manufacturer be made onshore of on operator's
appZioation for a SuppZementaZ Type Certificate by
obtaining the monufaot~rer's forma Z review prior to
authorizing any significant deviation from the approved
design.
The committee recognizes that this recommendation
introduces the need to define "significant" in a way
that will make it clear which items require a review by
the manufacturer-designer. Such items should be con-
fined strictly to those involving the continuing inte-
grity and safety of the design. One way to accomplish
this would be to require the Type Certificate holder to
identify all structural and functional system items es-
sential to safety by marking their location clearly on a
diagram associated with the maintenance program.
In carrying out this recommendation, the FAA needs
to take care that small and/or independent businesses do
not unjustly lose contracts as a result of the manufac-
turer's review, or that innovative improvements to air-
craft are not discouraged. The purpose of the recommen-
dation is to assure that safety is maintained by seeking
OCR for page 64
IMPROVING AIRCRAFT SAFETY/64
the guidance~of those responsible for the original
design, not to provide a power of approval or veto to
the manufacturer or imply that only it or a major repair
facility is capable of satisfactorily performing the
work.
Information System
The maintenance and operation activities of all air
carriers produce vast numbers of reports and service
data. Manufacturers, carriers, and the FAA collect,
organize, and transmit much of the available data and
information via their own systems. These systems, some
of which interconnect and overlap, are intended to keep
track of what is occurring with respect to the various
aircraft, to permit analyses that help identify trends
or predict future trouble spots, and, generally, to
provide information and advice to carriers and manu-
facturers that can be used in future improvements and
contributions to safety.
In addition to sharing the results of the FAA's
formal reporting and disseminating mechanisms, manu-
facturers receive information from their customer ser-
vice representatives stationed at the airlines as well
as from the carriers directly. They scrutinize all such
material to identify trends in the use of their equip-
ment that may suggest the need for a change in the de-
sign, manufacture or recommended maintenance, or that
may indicate significant operational occurrences. They
communicate their findings to the carriers by a variety
of means including regular newsletters and service
bulletins.
Each carrier is required to have a system for the
"continuing analysis and surveillance of the performance
and effectiveness" of its maintenance program.30
Specific records are to be maintained and monitored on
failures and other significant events. The carriers
collect data on maintenance and reliability character-
istics from a number of internal information systems--
e.g., unusual flight incident reports, flight log
reports of malfunctions, aircraft maintenance infor-
mation systems, daily operations reports, flight log
monitoring systems pertaining to engine reports, monthly
summaries of flight delays and cancellations, monthly
premature removal reports, and shop cost records.
OCR for page 65
65/Production and Maintenance
Many of the larger air carriers keep computerized
maintenance records on each of their airplanes. Such
records portray the aircraft's complete maintenance
history--the date and nature of all work performed and
the status of any deferred items, and the planned future
maintenance schedule. They also can call special atten-
tion to any unanticipated failures. Some airlines con-
duct a daily telephone conference with their various
repair stations across the country to receive and share
information concerning current failures and service dif-
ficulties. A few carriers also make sampling inspection
techniques a part of their maintenance programs to
ensure the monitoring of the aging process in their
equipment.
The airlines must submit daily Mechanical Relia-
bility Reports (MRR) to their assigned FAA maintenance
inspectors concerning the occurrence of 16 specified
types of aircraft failure, malfunction, or defect.
Thirteen of these involve events occurring in flight--
defined as "the period from the moment the aircraft
leaves the surface of the earth on takeoff until it
touches down on landing,"31 and widely interpreted to
exclude from the reporting requirements any incident oc-
curring while the plane is taxiing or otherwise on the
ground, including during maintenance.
Carriers also are required to submit Mechanical
Interruption Summaries (MIS), listing the causes of all
mechanical difficulties that result in the delay or can-
cellation of a flight.32 These are submitted approxi-
mately every 10 days and are reviewed for any unusual
trends by the Principal Maintenance Inspector. All
"major" alterations must be reported as well.*
FAA inspectors convert some of the information ac-
quired to Service Difficulty Reports (SDRs) and forward
these to the FAA Maintenance Analysis Center in Oklahoma
City. The center incorporates them into its data bank
together with all other reports it receives. The data
are analyzed to help identify problems and trends in
various categories of aircraft, components, and assem-
blies. The staff at the center examines the information
*The distinction between "major" and "minor" damage is
discussed on pages 68-69.
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IMPROVING AIRCRAFT SAFETY/66
and sends it on to the regional offices and to manufac-
turing inspectors.
The FAA also receives the National Transportation
Safety Board's aircraft accident reports and the reports
of special studies that the board conducts on recurrent
problems or trends noted from its knowledge of accidents
and incidents. Additionally, the FAA can request speci-
al computer runs of the Safety Board's accident data bank
to identify problems and failure trends in aircraft.
The information-gathering mechanisms presently used
by the FAA are a collection of individual systems that
have come into being at different times in response to
the identification of particular problems. In the past,
the Congress and the General Accounting Office33 have
found that the FAA's data base and communications system
are inadequate both in scope and practice for the modern
aviation system. The individual systems have little or
no common basis for cross-correlation of information.
Consequently, information in these data systems is often
not available in timely fashion, not able to be cross-
referenced, and not presented in a format that can be
easily used.
Recognizing this problem, the FAA has requested the
Department of Transportation's Transportation Systems
Center in Cambridge, Massachusetts, to develop a modern,
comprehensive information and data-processing system.
The committee was pleased to learn of this plan; how-
ever, we view the five years contemplated for its devel-
opment, testing, and implementation to be excessive.
Hence, the committee recommends that the FAA aooeZerate
its deveZopment of on effective info~mation-gathering
and data system. This system shouZd include assess to
the appropriate eZements of the monufaoturers' and
worriers' records.
A properly employed information system is indispens-
able to providing clues to, and early warning of, poten-
tial accidents. Critical to the effectiveness of such a
system are the following elements:
.
.
Information should be gathered and processed
quickly, and the system should be capable of
highlighting those items having possible
consequences for safety.
Additional information, beyond what is now
available, should be obtained, wherever
possible. The FAA needs to devote more
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67/Production and Maintenance
attention to the safety information passing
between and among the airlines and manufac-
turers that is now largely outside its purview.
The manufacturers should draft service bulle-
tins so as to provide the carriers with more
complete descriptions of the events or conse-
quences that the bulletins are intended to pre-
vent. By the same token, the carriers should
provide more details to the manufacturer identi-
fying the circumstances that led carriers to
request maintenance or alteration assistance.
Analysis of the data should be made by well-
qualified users.
The users of the system must be disciplined to
determine the cause of every incident, fail-
ure, or accident, to require that corrective
action be taken, and to provide feedback to all
concerned parties.
An example of a potentially effective information
system is the experimental Aviation Safety Reporting
System (ASRS), a project developed at the request of the
FAA by NASA. The committee was impressed, from the
briefing it received from NhSA, that this project is
already making a major contribution to safety, largely
because of the painstaking and detailed analysis of the
data that NASA is providing.
Since 1975, NASA has developed and operated the
safety reporting system, which permits confidential
reporting of safety problems and violations of pro-
cedures within the aviation system, including infor-
mation on human error. Anyone is permitted to file a
confidential report of observed or experienced safety
problems but, to date, pilots and air traffic control-
lers have been the principal reporting sources. In all,
more than 22,000 incidents have been reported. NASA has
published quarterly reports containing both the statis-
tical grouping of items and analyses of the more signif-
icant ones. In addition, special studies are conducted
at the request of the FAA or other parties. An adequate
statistical base now permits some trend studies to be
undertaken.
Importantly, in the NASA system, no single report is
regarded as trivial. Indeed, some seemingly trivial but
recurring items have turned out to be far from trivial.
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IMPROVING AI RCRAFT SAFETY/68
Examples of such problems, subsequently corrected, in-
clude ambiguous and hard-to-read approach chart infor-
mation for high density major airports, and taxiway/
runway near misses. The system also reveals altitude
assignment violations and ambiguous or contradictory
controller instructions.
Information of this kind--largely subjective and
anecdotal--is valuable and not available in the data
systems operated by the FAA. It should be included in
the proposed new data system. Although mechanics and
other ground personnel have not made use of the NASA
system so far, and there are some distinguishing or
identifying features in the data that would be submit-
ted that would make the confidentiality of such sources
difficult to preserve, the committee urges that the
system be extended to the reporting of maintenance
errors related to airworthiness concerns.
Damage to Primary Structure
The efficacy of the FAA's information and data
system depends in large part on its dependability for
reporting damage to the aircraft structure and associ-
ated repairs. Under Present regulations and Guidelines.
damage to aircraft structure is reported in different
ways depending on: the consequence of the occurrence,
where it occurred (flight or ground), what structure was
involved, the repair involved, interpretations of degree
of damage (e.g., significant or not significant), inter-
pretations of the type of repair (e.g., major or minor),
and, to a degree, a combination of these matters.
Depending on the descriptor, the requirements for
reporting and approval vary widely, thus increasing the
possibility that the FAA and the industry may fail to
identify an unsafe condition. An example of the con-
fusion existing in the present system involves the dis-
tinction between major and minor repairs. "Major" is
generally understood to refer to primary structure,
i.e., the principal load-carrying members, such as the
main wing beams. FAA regulations, however, are ambigu-
ous in distinguishing major and minor.
The regulations call for reporting the condition of
the aircraft's structure. The procedure for preparing
and submitting Alteration Reports and Repair Reports
~ ~ ~ ~ - ~:7 ~, ~_ i, ` a,
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69/Production and Maintenance
requires that: "Each certificate holder shall, promptly,
upon its completion, prepare a report of each major al-
teration or major repair of an airframe, aircraft en-
gine, propeller, or appliance of an aircraft operated by
it."34 Copies of reports concerning major alterations
are to be submitted to the FAA representative, while
copies of reports about major repairs are to be kept
available for inspection by the same representative.35
In another part of the regulations, the terms "major
repair" and "minor repair" are defined as follows:
"Major repair means a repair:
"1. That, if improperly done, might
appreciably affect weight, balance,
structural strength, performance,
powerplant operation, flight charac-
teristics, or other qualities affecting
airworthiness; or
"2. That is not done according to ac-
cepted practices or cannot be done by
elementary operations.
"Minor repair means a repair other than a major
repair.~36
In yet another place in
major repairs are defined as
"strengthening, reinforcing,
the regulations, airframe
those involving the
splicing, and manufac-
tur~ng ot primary structural members or their replace-
ment, when replacement is by fabrication such as rivet-
ing or welding."37
The application of these definitions requires con-
siderable interpretation by many individuals of variable
experience to determine whether or not to initiate a re-
pair report and thus enter the condition into the FAA's
information system. Such judgments, concerning whether
a major repair is reportable, and if so to whom, include
where the damage has occurred on the aircraft and, in
the case of structural damage, whether the aircraft was
in flight, or on the ground with engines operating.
It appears to the committee that some important
occurrences of structural damages may not be--indeed are
not likely to be--promptly and effectively reported and
reviewed by the FAA. For instance, the damage to the
aft pylon bulkhead, caused by a faulty maintenance pro-
cedure by Continental Airlines prior to the American
..
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IMPRoVING AIRCRAFT SAFETY/70
Airlines Chicago accident,* involved damage to a load-
carrying structure, but apparently was not a candidate
for reporting. According to the FAA Western Region, the
existing reporting system does not call for reporting
nonservice-related occurrences; therefore, the pylon
damage did not have to be reported. Arguably, if it had
been clear to Continental that such damage should have
been reported, the subsequent American Airlines acci-
dent might have been prevented.
It is obvious that these confusing requirements for
reporting accidents, incidents, occurrences, and repairs
of structural damage or deterioration need to be revised
to provide a clearer and more direct decision process
concerning what, when, and where to report. According-
ly, the committee recommends that the FAA require that
any damage to the primary structure of on aircraft, re-
gordZess of box the damage was caused, be reported.
This recommendation requires a commonly accepted de-
finition of primary structures, which are the principal
load-carrying members, as known by the designer. Iden-
tification of primary structures by maintenance personnel
would be made easier by requiring the manufacturer to
include sketches of the aircraft structural skeleton,
which are normally produced during the aircraft design
stage, in the maintenance manual.
should be clearly marked.
*See Appendix B.
Primary structures
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Representative terms from entire chapter:
faa inspectors
