# AD 55-25-04: Tail Cone Skin Reinforcements

- 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- Superseded by: Nothing supersedes this AD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/C5B424A71465422486256A4D0050242C.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/55-25-04

## The airworthiness directive

55-25-04 SIKORSKY: Applies to All Model S-55 Helicopters.

Compliance required as indicated.

A recent failure of the tail cone skin in the area where the tail cone is spliced to the fuselage has been reported in a Model S-55 helicopter. Since this is the means of attaching the tail cone to the fuselage and to preclude further failures, the following inspections and reinforcements for the splice area are considered necessary.

1. Tail cones with less than 1,500 hours, add reinforcements at the next major inspection or within the next 150 hours.

2. Tail cones with 1,500 hours to 2,000 hours, inspect the skin for cracks at the next major inspection or within the next 150 hours. If no cracks are found, add reinforcements. If cracks are found, replace the skin and add reinforcements.

3. Tail cones with 2,000 hours or more, inspect the skin for cracks at the next intermediate inspection or within the next 50 hours. If no cracks are found, add reinforcements. Ifcracks are found, replace the skin and add reinforcements.

4. The inspection procedures to be followed, the reinforcements to be added and the method of attaching the reinforcements are explained in detail in Sikorsky Information Circular No. 1420-632.

## 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/55-25-04/models.md
Every aircraft: https://openairdocs.org/ad/55-25-04/aircraft.md

Its text cites no advisory circulars or STCs.

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