AD 99-19-01
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Continental Motors | GTSIO-520-C | Airworthiness Directives; Teledyne Continental Motors O-470, IO-470, TSIO-470, IO-520, TSIO-520, LTSIO-520, GTSIO-520, IO-550, TSIO-550, and TSIOL-550 Series Reciprocating Engines |
| engine | Continental Motors | GTSIO-520-D | Airworthiness Directives; Teledyne Continental Motors O-470, IO-470, TSIO-470, IO-520, TSIO-520, LTSIO-520, GTSIO-520, IO-550, TSIO-550, and TSIOL-550 Series Reciprocating Engines |
| engine | Continental Motors | GTSIO-520-E | Airworthiness Directives; Teledyne Continental Motors O-470, IO-470, TSIO-470, IO-520, TSIO-520, LTSIO-520, GTSIO-520, IO-550, TSIO-550, and TSIOL-550 Series Reciprocating Engines |
| engine | Continental Motors | GTSIO-520-F | Airworthiness Directives; Teledyne Continental Motors O-470, IO-470, TSIO-470, IO-520, TSIO-520, LTSIO-520, GTSIO-520, IO-550, TSIO-550, and TSIOL-550 Series Reciprocating Engines |
| engine | Continental Motors | GTSIO-520-H | Airworthiness Directives; Teledyne Continental Motors O-470, IO-470, TSIO-470, IO-520, TSIO-520, LTSIO-520, GTSIO-520, IO-550, TSIO-550, and TSIOL-550 Series Reciprocating Engines |
| engine | Continental Motors | GTSIO-520-K | Airworthiness Directives; Teledyne Continental Motors O-470, IO-470, TSIO-470, IO-520, TSIO-520, LTSIO-520, GTSIO-520, IO-550, TSIO-550, and TSIOL-550 Series Reciprocating Engines |
| engine | Continental Motors | GTSIO-520-L | Airworthiness Directives; Teledyne Continental Motors O-470, IO-470, TSIO-470, IO-520, TSIO-520, LTSIO-520, GTSIO-520, IO-550, TSIO-550, and TSIOL-550 Series Reciprocating Engines |
| engine | Continental Motors | GTSIO-520-M | Airworthiness Directives; Teledyne Continental Motors O-470, IO-470, TSIO-470, IO-520, TSIO-520, LTSIO-520, GTSIO-520, IO-550, TSIO-550, and TSIOL-550 Series Reciprocating Engines |
| engine | Continental Motors | GTSIO-520-N | Airworthiness Directives; Teledyne Continental Motors O-470, IO-470, TSIO-470, IO-520, TSIO-520, LTSIO-520, GTSIO-520, IO-550, TSIO-550, and TSIOL-550 Series Reciprocating Engines |
| engine | Continental Motors | IO-470-A | Airworthiness Directives; Teledyne Continental Motors O-470, IO-470, TSIO-470, IO-520, TSIO-520, LTSIO-520, GTSIO-520, IO-550, TSIO-550, and TSIOL-550 Series Reciprocating Engines |
Unsafe Condition
Crankshaft failure due to cracks in the No. 2 and No. 5 (and No. 8 for geared engines) cheeks caused by damage during counterweight bushing installation, leading to total engine power loss, in-flight failure, or forced landing.
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Required Actions
Conduct a one-time visual and ultrasonic inspection of No. 2, No. 5 (and No. 8 for geared engines) crankshaft cheeks per TCM CSB 99-6A. Replace crankshafts with cracked cheeks prior to further flight. Inspections must be performed by TCM-trained personnel.
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Compliance Time
Before further flight for cracked crankshafts; inspections must be completed within 500 hours time-in-service (TIS) for engines not yet inspected.
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Affected Aircraft
TCM O-470, IO-470, TSIO-470, IO-520, TSIO-520, LTSIO-520, GTSIO-520, IO-550, TSIO-550, TSIOL-550 engines manufactured/rebuilt between Jan-Dec 1998, plus GTSIO-520 series and additional engines listed by serial numbers in TCM MSB 99-3C.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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