AD 75-11-09
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Lockheed Martin Corporation | L-1011-385-1 | LOCKHEED-CALIFORNIA COMPANY Model L-1011-385-1 Series Airplanes |
| aircraft | Lockheed Martin Corporation | L-1011-385-1-14 | LOCKHEED-CALIFORNIA COMPANY Model L-1011-385-1 Series Airplanes |
| aircraft | Lockheed Martin Corporation | L-1011-385-1-15 | LOCKHEED-CALIFORNIA COMPANY Model L-1011-385-1 Series Airplanes |
Unsafe Condition
Failure of Belleville springs in counterbalances P/N 671827-107, -109, -113 could cause inoperative Type I emergency door actuation system, rendering the most rearward left and right doors inoperative in emergency mode.
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Required Actions
Reduce spring prewind per SB 093-52-072 for P/N 671827-113 counterbalances within 300 flight hours. Perform operational checks on doors every 1,600 flight hours until replacement. Replace P/N 671827-113 counterbalances with P/N 671827-107/-109 or -115/-117 within 8,000 flight hours. Mark defective counterbalances to prevent reuse.
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Compliance Time
Within 300 additional flight hours after May 30, 1975, and at intervals not to exceed 1,600 flight hours thereafter until replacement. Replacement required within 8,000 additional flight hours after May 30, 1975.
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Affected Aircraft
Lockheed-California Company Model L-1011-385-1 Series airplanes with counterbalances P/N 671827-107, -109, or -113.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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