# AD 47-21-22: Engine Mounting Bolt Lock Washers

- Type: Airworthiness directive
- Status: Current
- Products: Sky Enterprises RC-3
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Registered aircraft: 126 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/ABEC513EAD4F10CF86256A5600668CF9.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/47-21-22

## The airworthiness directive

47-21-22 REPUBLIC: (Was Service Note 2 of AD-769-2.) Applies to Model RC-3 Aircraft.

Inspection required before next flight and at each subsequent 25 hours of operation.

If no tab type lockwashers are installed, check tightness of engine mounting bolts to torque of 25 foot-pounds on 3/8-inch bolts and 30 foot-pounds on 7/16-inch bolts. If it is found that loosening has occurred it will be necessary to install tab type lockwashers under all engine mounting bolts. (AMI P/N 15175 for 3/8-inch bolts, AMI P/N 15176 for 7/16-inch bolts.)

If tab type lockwashers have been installed previously and tabs are in place, inspection is required only at the regular 100-hour periods.

(Aircooled Motors Service Bulletin No. 47 pertains to this subject.)

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A-769](https://openairdocs.org/tcds/A-769): Sky Enterprises Inc.; names 1 of 1 models: RC-3

## Registered aircraft it may apply to (OpenAirDocs)

Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment.

- Aircraft: 126 (126 by airframe model, 0 by engine model)
- Makers: Republic 122, Downer 2, Republic Aviation Corp USA 1, Simuflight Seattle-1-Stol 1

Models with the most aircraft:

- [Republic RC-3](https://openairdocs.org/model/republic-rc-3): 122 aircraft (airframe model)
- [Downer RC-3](https://openairdocs.org/model/downer-rc-3): 2 aircraft (airframe model)
- [Republic Aviation Corp USA SEABEE RC-3](https://openairdocs.org/model/republic-aviation-corp-usa-seabee-rc-3): 1 aircraft (airframe model)
- [Simuflight Seattle-1-Stol RC-3](https://openairdocs.org/model/simuflight-seattle-1-stol-rc-3): 1 aircraft (airframe model)

All 4 models: https://openairdocs.org/ad/47-21-22/models.md
Every aircraft: https://openairdocs.org/ad/47-21-22/aircraft.md

Its text cites no advisory circulars or STCs.

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