Fuselage:

• Upper cockpit longerons

  • hookslot cracking

  • small critical crack sizes

  • low inspection intervals

  • material change/redesign

  • force-wide modification in progress

In addition to the fatigue cracking problems, the San Antonio ALC identified the following SCC problems on the T-38:

Fuselage:

• Cockpit longerons

  • upper and lower longerons

  • 7075-T6 aluminum

  • cracking of the forward splice at fuselage station 284

  • inspect and repair (interim)

  • material change/redesign

  • force-wide modification of upper longerons

  • force-wide inspection/repair of lower longerons

• Fuselage forgings

  • bulkheads at fuselage stations 325 and 362; formers at fuselage stations 332, 487, and 508

  • temporary repairs

  • material/design changes

  • force-wide modification of bulkhead at fuselage station 325

  • inspect and repair remaining changes

The following honeycomb deterioration problems were also noted:

• Horizontal stabilizer

  • core corrosion attributable to water intrusion

  • improved bonding being implemented

• Landing gear strut door

  • core corrosion attributable to water intrusion

  • superplastic formed/diffusion-bonded titanium redesign

  • current preferred spare

Based on the above, it is apparent that the San Antonio ALC will continue to face a major challenge to protect the safety and prolong the service life of the T-38 for another 25+years as indicated in Chapter 2 of this report. Most of the cracking problems noted are safety-of-flight concerns. As noted in Chapter 5, the committee recommends that this aircraft be given high priority in updating the DADTA and obtaining an improved estimate of economic service life.