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.



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