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In-Service Performance Criteria
for Aircraft Interiors
Hanns-Ioerg Betz
*
INTRODUCTION
Besides flammability, toxicity, smoke emission, wear-resistance, and other technical
requirements that are defined in detailed specifications by the aircraft manufacturers, special
requirements out of the service experience had to be incorporated in the design of aircraft
interiors. Often the specification requirements do not meet the "in-service requirements criteria."
In order to create a comfortable feeling for the passenger the aircraft interior must provide
durable performance while showing a clean, pleasing, and comfortable cabin without any visible
damage.
INFLUENCE FACTORS TO THE CABIN PERFORMANCE
An ideal airplane interior would have outstanding performance, would not need any
maintenance, and would allow a system of servicing that would not damage the furnishings.
Unfortunately, up to now and in the near future this is not feasible. Airlines recognize that they
are dealing with people and are generally content with the low incidence of vandalism.
There are several factors that influence cabin performance. These include:
design and manufacturing,
material performance,
passengers,
service personnel, and
· mechanics.
EXAMPLES OF PERFORMANCE PROBLEMS
Material Performance
The first thing that passengers notice when they board an airplane is the floor covering.
Directly, they can see dirt and wear caused by trolley wheels, shuffling shoes, and uneven floor
panels. Panel gaps, moving panels, and washers not properly attached allow bolts to show clear
marks on both nontextile and textile floor coverings especially on nontextile floor coverings that
*Cabin and Cargo Systems, Lufthansa German Airlines, Frankfurt, Germany.
197
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Improved Fire- and Smoke-Resistant Materials
are installed in areas prone to corrosion or heavy loads. Slip resistance must be maintained
throughout the year, especially in the winter, to provide safety for the passengers and crew.
During the winter, floors can be made slippery by residues from anti-icing fluids, increasing the
potential for mishaps.
The next items that passengers see and fee! are the seats. The performance metric for seat
cushion behavior is the indentation hardness. Not apparent to the passengers are the safety-
enhancing characteristics of the fire-blocking layers. Aged fire-blocking layers may no longer
meet fire-blocking star~dards as currently specified. Regular tests of used cushions are carried
out to maintain confidence in the material performance.
Generally, passengers do not notice inactive bulbs in the lighting system unfit a specific
situation occurs where the lights are needed (e.g., when there is a need for a reading light,
passenger signals, or floor path markings). Since it is too late to solve the problem during the
flight, the airlines do frequent inspections and repairs of these systems, which create unnecessary
costs.
Passengers and Crews
During boarding, passengers may have problems in stowing their hand luggage. The
allowable number and size of carry-on bags are defined by the airlines and the International Air
Transport Association. Nevertheless, passengers often bring more luggage onboard than allowed.
Hand luggage is sometimes too large to fit into the stowage bin opening which results in the use
of force to stow the luggage. The consequence is damaged hinges, doors, and structures.
Hard hand luggage or bags with special latches can damage walls and decorative
laminates, as they are squeezed through the narrow aisles. Thin laminates and lightweight panels
are damaged easily and then have to be repaired.
Toilets are used to dispose of waste paper towels, diapers? beer bottles, plastic glasses,
and sometimes passports, which clogs toilets and disturbs the next passenger, who will have an
unusable toilet.
REASON FOR PERFORMANCE PROBLEMS
Other reasons for performance problems are caused by servicing and maintenance
personnel.
Servicing Personnel
Catering, cargo loading, cleaning, toilet-servicing, and water-servicing personnel are
generally low-pa~d, low-skilled people. After a short training course, they are required to learn
"on the job." They are always under time pressure, as they do not want to be responsible for
departure delays. When problems occur, they try to solve the problems by themselves without
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Hanns-J6erg Betz
199
detailed knowledge of the situation (e.g., resetting systems, trying to switch systems, or trying
to override a system).
Transporting heavy trolleys with additional parts on top will damage floor panels and
floor covering. In cargo compartments, decompression panels are damaged and require repairs.
Maintenance Personnel
Maintenance mechanics are responsible for keeping the cabin in good condition in terms
of performance and appearance. Problems are identified using the cabin log book, the technical
log book, quick examinations by mechanics during transits, and specified maintenance checks.
In the beginning of the service of a new aircraft, the documentation is incomplete and
background information on potential problem areas is not available. During this time, the
mechanics are learning from experience and on-thejob training, necessitating additional
inspections and functional checks to verify that performance has not been compromised.
Design deficiencies cost a significant amount of additional work for the mechanics. The
first modifications of the parts improve the situation. If sufficient spare parts are available, the
mechanic may exchange the parts without registering a complaint, which allows maintenance
trends or poor performance to remain unsubstantiated.
PERFORMANCE CRITERIA
The appearance and function of the cabin needs to be maintained to a high standard. The
aircraft cabin is regularly checked according to maintenance checks, intervals, and tasks. The
maintenance checks take the following items into consideration:
continuous safety,
· quality for passengers,
materials, and
costs per part.
Continuous Safety
Safety in an aircraft cabin is mandatory. Therefore, regular checks are required by the
crews and by the mechanics. At the beginning of the flight, all passengers are asked to become
familiar with in-flight safety requirements and evacuation requirements.
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Improved Fire- aM Smoke-Resistant Materials
FI~nability Requirements
In the case of component flammability, it is difficult to ensure the quality and compliance
with the applicable rules. Therefore, it is necessary to only allow the use of materials that meet
regulatory requirements for flammability.
One means to ensure continued compliance with flammability requirements is to have
spares in storage of all parts that may be damaged. Since this is obviously not feasible, the
mechanic must have He materials and methods available to repair parts that allow continued
compliance with performance requirements. Repair matenals and spare parts must meet the latest
standard of flammability requirements. There should also be assurance that the component design
is tolerant of an acceptable level of damage without influence on the flammabiliyv requirements.
Prevention of Cabin Malfunction
, ~
Damage may occur due to improperly latched bins, stowed and latched trolleys, and
ovens. Therefore, proper checks of all latches before and during flight need to be performed by
the cabin crew. Bins not properly locked may cause damage aunt could represent a cianger to
passengers.
Quality for Passengers
To achieve the maximum comfort for the passengers and reduce maintenance,
improvements in aircraft interior seats, seat cushions, galleys, lavatory systems, entertainment,
cabin lighting systems, and air-conditioning systems are needed.
Ideally, seats should not have to be inspected at all and should always function properly
and provide complete comfort. Colors, fabrics, and surfaces are chosen that hide dirt and are
easily cleaned. Ashtrays are designed to be cleaned without any damage. Seat cushions are
designed to fit in the seat structure without internal tearing.
The appearance of a new replacement part shouic! not be significantly different from the
original installation. Repairs of minor damage need to be easily hidden.
A significant amount of maintenance and a number of modifications are required to keep
cabin systems, such as lavatories, water systems, and entertainment systems, functioning. in case
of system problems during flights, notification of the crew and remediation should occur without
disruption of passengers.
Airlines need to continue to improve the comfort and convenience of travel for
passengers. Therefore, Lufthansa and other airlines are searching for new developments or
features for in-flight entertainment and other items to better please our passengers. It is also
important to heed trends in passengers' demands or complaints.
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Nanns-J6erg Betz
201
Materials
The technical performance requirements for the cabin materials are defined in detailed
specifications. Some of the characteristics controlled in materials specifications include:
flammability,
low-cost producibility,
resistance to aging,
color stability and reproducibility,
mechanical properties,
ease of repair, and
optimized weight.
The weight has an important influence on the fuel costs, payload range, and performance.
Costs per Part
Many Lufthansa customers complain about high fares for flights. We are often shocked
as well with the cost of an interior part. But there are significant nonrecurring and certification
costs associated with the development of a part to be installed in an aircraft. Also, the
manufacturer has to guarantee excellent product quality and quality control that meet the
requirements of the specification. In addition to these costs, the airline has to account for the
maintenance, overhaul costs, part service life, and product improvements. These additional costs
may reduce the performance tremendously. Having parts in the shop for repair too often results
in modification or exchange of the pad. Service and maintenance experience for cabin
components are reported to the supplier and aircraft manufacturer. These experiences may lead
to modifications to improve the performance. Product support is very important to enable
keeping parts in good condition.
Maintenance and In-Service Costs
Maintenance actions are always seen in connection with high operating costs. These
activities range from daily monitoring to an overhaul or D-Check, which has to be performed,
in most cases, every 5 to 6 years. At this time, a 747 will have carried about 200,000 to
300,000 passengers per year. Therefore, the frequency of the maintenance inspections is
important to achieve a positive result. For economic reasons, it is necessary to reduce the
duration and downtime of the airplane. To reduce the downtime, it is necessary to either increase
the manpower or to make maintenance activities easy. Accessibility of parts for maintenance
actions is very important. Otherwise, delays will result, and passengers will become disappointed
or angry. Further delays could lead to other problems such as rotation problems, disruption of
inspection intervals of other airplanes, and cancellation of flights (with airline responsibility for
hose! accommodations).
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Improved Fire- aru] Smoke-Resistant Materials
Airlines are looking to reduce the manpower needed to perform maintenance ant! to
perform the work with lower-qualified personnel. These trends reinforce the need to improve
cabin design and materials performance to a point where, instead of performing maintenance,
ground personnel need only check the function and appearance of the cabin.
CONCLUSION
Aircraft cabin performance criteria are influenced by
· frequency of required actions,
material,
people, and
· design.
Cost and quality need to be optimized for
weight, part costs, and in-service costs;
safety and quality for passengers; and
lifetime costs.
Airlines need a passenger-pleasing ant! safe airplane at all times with reductions in
required maintenance.
Representative terms from entire chapter:
cabin performance
