AD 76-07-07
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Cessna Aircraft Company | 421C | Airworthiness Directives; CESSNA Model 421C Airplanes |
Unsafe Condition
Leakage of fuel and an engine nacelle fire due to deterioration of the P/N S1129-03-0304 hose assembly fire sleeve and potential hardening, cracks, or seepage in the hose when routed too close to exhaust system surfaces.
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Required Actions
Inspect the P/N S1129-03-0304 hose assembly's fire sleeve for whitening or deterioration. If found, inspect the hose for hardening, cracks, or seepage and replace if necessary, maintaining at least four inches from exhaust surfaces. Install a new fire sleeve or reposition the existing one. Within 25 hours' time in service after the effective date, replace the hose assembly with Cessna P/N 5100109-56 steel line as per Service Kit SK421-69. Paragraph A is no longer applicable after completing Paragraph B.
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Compliance Time
Prior to the next and each subsequent flight for Paragraph A; within 25 hours' time in service after the effective date for Paragraph B.
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Affected Aircraft
Cessna Model 421C (Serial Numbers 421C0003 thru 421C0052 except 421C0008, 421C0017, 421C0019, 421C0026, 421C0039, 421C0045, 421C0046, and 421C0048)
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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