AD 50-31-01
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Cessna Aircraft Company | 120 | Airworthiness Directives; CESSNA Model 120 and 140 Airplanes |
| aircraft | Cessna Aircraft Company | 140 | Airworthiness Directives; CESSNA Model 120 and 140 Airplanes |
| aircraft | Cessna Aircraft Company | 140A | Airworthiness Directives; CESSNA Model 120 and 140 Airplanes |
Unsafe Condition
Fin spar fatigue failures have occurred in flight due to inadequate inspection difficulty, resulting in flange buckles or cracks in the spar and spar reinforcing channel.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Inspect the fin spar for flange buckles or cracks using an 8-power magnifying glass. If failure exists, replace the spar with one incorporating a 0.051 24ST alclad fin spar reinforcing channel (Cessna P/N 0431129 or equivalent). If no failure, install reinforcing angles (Cessna P/N 0431145 and 1431145-1 or equivalent). For spot-welded aircraft, drill out spots with a No. 30 drill, pry skin loose, inspect, and replace spot welds with 1/8-inch rivets or use larger rivets if damage prevents proper filling.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Compliance required as soon as possible and not later than August 1, 1950, except for spot-welded aircraft which must comply by September 1, 1950.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Cessna Model 120 and 140 aircraft, serial numbers 8001 to 15035 inclusive, where the 0.051 reinforcing channel or 0.040 reinforcing angles have not been installed.
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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