AD 77-13-22
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Continental Motors | GTSIO-520-C | TELEDYNE CONTINENTAL MOTORS Model IO-520-A, -B, -BA, -C, -D, -E, -F, -J, -K, -L, and -M; TSIO-520-B, -C, -D, -E, -G, -H, -J, -K, -L, and -N; GTSIO-520-C, -D, -F, and -H Engines |
| engine | Continental Motors | GTSIO-520-D | TELEDYNE CONTINENTAL MOTORS Model IO-520-A, -B, -BA, -C, -D, -E, -F, -J, -K, -L, and -M; TSIO-520-B, -C, -D, -E, -G, -H, -J, -K, -L, and -N; GTSIO-520-C, -D, -F, and -H Engines |
| engine | Continental Motors | GTSIO-520-F | TELEDYNE CONTINENTAL MOTORS Model IO-520-A, -B, -BA, -C, -D, -E, -F, -J, -K, -L, and -M; TSIO-520-B, -C, -D, -E, -G, -H, -J, -K, -L, and -N; GTSIO-520-C, -D, -F, and -H Engines |
| engine | Continental Motors | GTSIO-520-H | TELEDYNE CONTINENTAL MOTORS Model IO-520-A, -B, -BA, -C, -D, -E, -F, -J, -K, -L, and -M; TSIO-520-B, -C, -D, -E, -G, -H, -J, -K, -L, and -N; GTSIO-520-C, -D, -F, and -H Engines |
| engine | Continental Motors | IO-520-A | TELEDYNE CONTINENTAL MOTORS Model IO-520-A, -B, -BA, -C, -D, -E, -F, -J, -K, -L, and -M; TSIO-520-B, -C, -D, -E, -G, -H, -J, -K, -L, and -N; GTSIO-520-C, -D, -F, and -H Engines |
| engine | Continental Motors | IO-520-B | TELEDYNE CONTINENTAL MOTORS Model IO-520-A, -B, -BA, -C, -D, -E, -F, -J, -K, -L, and -M; TSIO-520-B, -C, -D, -E, -G, -H, -J, -K, -L, and -N; GTSIO-520-C, -D, -F, and -H Engines |
| engine | Continental Motors | IO-520-BA | TELEDYNE CONTINENTAL MOTORS Model IO-520-A, -B, -BA, -C, -D, -E, -F, -J, -K, -L, and -M; TSIO-520-B, -C, -D, -E, -G, -H, -J, -K, -L, and -N; GTSIO-520-C, -D, -F, and -H Engines |
| engine | Continental Motors | IO-520-C | TELEDYNE CONTINENTAL MOTORS Model IO-520-A, -B, -BA, -C, -D, -E, -F, -J, -K, -L, and -M; TSIO-520-B, -C, -D, -E, -G, -H, -J, -K, -L, and -N; GTSIO-520-C, -D, -F, and -H Engines |
| engine | Continental Motors | IO-520-D | TELEDYNE CONTINENTAL MOTORS Model IO-520-A, -B, -BA, -C, -D, -E, -F, -J, -K, -L, and -M; TSIO-520-B, -C, -D, -E, -G, -H, -J, -K, -L, and -N; GTSIO-520-C, -D, -F, and -H Engines |
| engine | Continental Motors | IO-520-E | TELEDYNE CONTINENTAL MOTORS Model IO-520-A, -B, -BA, -C, -D, -E, -F, -J, -K, -L, and -M; TSIO-520-B, -C, -D, -E, -G, -H, -J, -K, -L, and -N; GTSIO-520-C, -D, -F, and -H Engines |
Unsafe Condition
Crankcase cracks may progress into crankcase failure, particularly in the upper rear stud area of number 2 and 6 cylinders, magneto pads, and between cylinder mounting bases.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Within 50 hours time in service after the effective date, inspect the engine crankcase for cracks. If no cracks found, reinspect every 100 hours until replaced with an improved crankcase. If cracks found, stop-drill and epoxy fill non-critical cracks under specified conditions, replace crankcase if critical cracks exist, and install backbone bolt kit for certain models. Logbook entries and FAA adjustments for inspection intervals are required.
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Compliance Time
within the next 50 hours time in service after the effective date of this A.D.
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Affected Aircraft
TELEDYNE CONTINENTAL MOTORS engines: IO-520-A, -B, -BA, -C, -D, -E, -F, -J, -K, -L, -M; TSIO-520-B, -C, -D, -E, -G, -H, -J, -K, -L, -N; GTSIO-520-C, -D, -F, -H models not incorporating identification markings in Table 1. Excludes engines with specified serial numbers.
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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