# AD 54-20-02: Support Assembly Cracks

- Type: Airworthiness directive
- Status: Current
- Products: Orlando Helicopter Airways HRS-1/CH-19, HRS-3/H-19B, S-55, S-55B and S-55C
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Rotorcraft
- Registered aircraft: 17 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/41CE1F7FC6CDA65A86256A4D00501D97.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/54-20-02

## The airworthiness directive

54-20-02 SIKORSKY: Applies to All Model S-55 Helicopters.

Compliance required as indicated.

In order that cracks in the fore and aft transmission support assemblies (S14-20-2503) may be detected, these assemblies should be inspected daily, without removing the support assemblies from the helicopter, in accordance with the following procedure:

1. Remove the paint, grease and foreign matter from all welds and from the areas of the tubes within 3 inches of a weld on both upper and lower ends.

2. Inspect for cracks all areas of the tubes within 2 inches of a weld and all welds visually, and, where possible, with the assistance of a 5- to 7-power glass.

3. Assemblies found with a crack should be replaced immediately.

4. Protect the exposed areas of metal with any suitable corrosion preventive.

The manufacturer is presently investigating the reasons for the occurrence of such cracks and a permanent repair is expected in the near future which, when incorporated, will make these daily inspections unnecessary. These inspections are in addition to those required by AD 54-16- 01.

(Revision C to Sikorsky Information Circular No. 1435-383 covers this same subject.)

When transmission support, S14-20-4603, is installed in place of support S14-20-2503, the above inspection may be performed at every intermediate inspection rather than on a daily basis.

(Sikorsky Service Information Circular No. 1420-548, dated December 3, 1954, covers the installation instructions.)

## Affected data sheets (2) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 1H4](https://openairdocs.org/tcds/1H4): Centerpointe Aerospace Inc.; names 3 of 3 models: S-55C, S-55, S-55B
- [TCDS HR1SO](https://openairdocs.org/tcds/HR1SO): Orlando Helicopter Airways Inc.; names 2 of 10 models: HRS-3/H-19B, HRS-1/CH-19

## 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: 17 (17 by airframe model, 0 by engine model)
- Makers: Sikorsky 15, Sikorsky/Orlando 1, Sikorsky/Vertical 1

Models with the most aircraft:

- [Sikorsky S-55B](https://openairdocs.org/model/sikorsky-s-55b): 9 aircraft (airframe model)
- [Sikorsky S-55](https://openairdocs.org/model/sikorsky-s-55): 3 aircraft (airframe model)
- [Sikorsky S55B](https://openairdocs.org/model/sikorsky-s55b): 3 aircraft (airframe model)
- [Sikorsky/Orlando S-55](https://openairdocs.org/model/sikorsky-orlando-s-55): 1 aircraft (airframe model)
- [Sikorsky/Vertical S-55](https://openairdocs.org/model/sikorsky-vertical-s-55): 1 aircraft (airframe model)

All 5 models: https://openairdocs.org/ad/54-20-02/models.md
Every aircraft: https://openairdocs.org/ad/54-20-02/aircraft.md

Its text cites no advisory circulars or STCs.

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