AD 90-14-08
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Pratt & Whitney Division | JT9D-7R4D | PRATT & WHITNEY Models JT9D-7R4D and -7R4E Engines |
| engine | Pratt & Whitney Division | JT9D-7R4E | PRATT & WHITNEY Models JT9D-7R4D and -7R4E Engines |
Unsafe Condition
Engine overtemperature and loss of power or engine shutdown inflight due to improper bleed trim and control adjustments.
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Required Actions
Adjust engine vane and bleed control (EVBC) to specified EPR bleed trim settings, modify fuel control unit (FCU) decel schedule, incorporate specified modifications to EVBC and FCU components, inspect and replace worn 3.0 bleed valve linkage, install 3.0 bleed dampers at next shop visit, and restore fan module compressor blades at next overhaul.
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Compliance Time
Within 5 calendar days or 50 cycles in service after the effective date (July 2, 1990), whichever occurs later, for engines with 4,000+ cycles since HPC overhaul; within 15 calendar days or 150 cycles in service after effective date, but not exceeding 4,050 cycles since HPC overhaul, for engines with less than 4,000 cycles. Some requirements must be done prior to July 31, 1990, or at next shop/overhaul.
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Affected Aircraft
Pratt & Whitney JT9D-7R4D and -7R4E engines installed on Boeing B767 aircraft.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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