# AD 56-16-03: Main Rotor Blade Inspection

- Type: Airworthiness directive
- Status: Current
- Products: Orlando Helicopter Airways HRS-1/CH-19, HRS-3/H-19B, S-51, 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- Superseded by: Nothing supersedes this AD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/06EB5E55C1AE7AEB86256A4D00502ABD.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/56-16-03

## The airworthiness directive

56-16-03 SIKORSKY: Applies to All Model S-55 Helicopters With S14-10-2000-1, -2, - 3, -4, and -5 Main Rotor Blades Bearing Serial Numbers 100-3700 Inclusive, and All Model S-51 Helicopters With S10-10-2065 Series Main Rotor Blades Bearing Serial Numbers 100-3700 Inclusive.

Compliance required as indicated.

Main rotor blades of the S10-10-2065 Series on the S-51 and of the S14-10-2000-1, -2, - 3, -4 and -5 Series on the S-55 have been found with fine cuts on the spar beneath the edges of the pockets. These cuts are believed to be a result of repairs to blade pockets and constitute serious stress raisers which may materially affect the service life of the blades. Inspections are to be accomplished as indicated below. The necessary preparations for inspections, the inspections, the finishing of serviceable blades and the rework of salvable blades are to be in accordance with the procedures recommended in Sikorsky Service Information Circular No. 676 for the S-51 and 1410-669 for the S-55.

1. All blades with less than 500 hours service since manufacture or complete rebuilding prior to May 1953, should be inspected as soon as practicable but prior to the accumulation of 500 hours.

2. All blades with 500 hours or more service since manufacture or complete rebuilding prior to May 1953, should be inspected as soon as practicable but not later than August 15, 1956.

3. Blades found to have no cuts may be returned to service after refinishing.

4. S-55 blades with less than 1,200 hours service and S-51 blades with less than 1,000 hours service and found to have cuts on the top or bottom may be salvaged.

5. Blades found to have cuts on the back are to be returned to the manufacturer for evaluation.

6. S-55 blades with 1,200 hours or more service and S-51 blades with 1,000 hours or more service and found to have cuts on the top, bottom or back are to be returned to the manufacturer for evaluation.

## Affected data sheets (3) (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
- [TCDS H-2](https://openairdocs.org/tcds/H-2): Sikorsky Aircraft Corporation; names 1 of 1 models: S-51

## 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/56-16-03/models.md
Every aircraft: https://openairdocs.org/ad/56-16-03/aircraft.md

Its text cites no advisory circulars or STCs.

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