AD 71-21-06
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Piper Aircraft Inc. | PA-23-250 (Navy UO-1) | Airworthiness Directives; Piper Model PA 23-250 Airplanes |
Unsafe Condition
Failure of the existing alternate air flexible duct (P/N 22502-65) could allow fire to pass through the engine firewall in the event of a powerplant fire.
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Required Actions
Replace the existing alternate air flexible duct P/N 22502-65 with new fireproof duct P/N 48076-02, following Piper Service Bulletin 334 or an equivalent approved duct. Compliance may be requested to be extended by the FAA.
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Compliance Time
within the next 50 hours' time in service after the effective date of this airworthiness directive unless already accomplished
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Affected Aircraft
Piper Aircraft Inc. Model PA-23-250 (Navy UO-1) serial numbers 27-4053, 27-4226 through 27-4563 inclusive, 27-4565 through 27-4579 inclusive, 27-4581 through 27-4617 inclusive, 27-4619 through 27-4627 inclusive, 27-4630 through 27-4636 inclusive.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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