# AD 76-18-01: Tail boom support strut

- Type: Airworthiness directive
- Status: Historical
- Products: Schweizer 269A, 269A-1, 269B, 269C, 269C-1 and 269D
- Effective: September 7, 1976
- Superseded by: [AD 2001-25-52](https://openairdocs.org/ad/2001-25-52)
- Product type: Aircraft, Rotorcraft
- Amendment: 39-2707
- Registered aircraft: 428 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/058793BC1B44D36686256A39004E0ECD.0001
- DRS record last changed: August 7, 2025
- Page: https://openairdocs.org/ad/76-18-01

## The airworthiness directive

76-18-01 HUGHES HELICOPTERS: Amendment 39-2707. Applies to Model 269 series (including military Model TH-55A) helicopters certificated in all categories equipped with tail boom support strut assemblies P/N 269A2015 or P/N 269A2015-5, tail boom center attach fitting P/N 269A2324 and center frame aft cluster fittings P/N 269A2234(LH) and 269A2235(RH).

Compliance required as indicated, unless already accomplished.

To prevent fatigue failure of the tail boom support strut installation and resultant loss of the helicopter flight controllability accomplish the following:

  (a) For helicopters equipped with tail boom support strut assemblies P/N 269A2015 or 269A2015-5, within the next 50 hours time in service after the effective date of this AD and thereafter at intervals not to exceed 50 hours time in service from the last inspection until the modifications of paragraph (c) are accomplished:

  (1) Support the tail boom and remove the tail boom support strut assemblies P/N 269A2015 on Hughes Model 269A, 269A-1, 269B and military TH-55A helicopter or P/N 269A2015-5 on Hughes Model 269C helicopter in accordance with the Hughes 269 Helicopter Basic Handbook of Maintenance Instructions Section 13;

  (2) Visually inspect the tail boom support strut aluminum end fittings for deformation or damage and visually inspect the tail boom support strut aluminum end fittings for cracks using the dye penetrant method in accordance with Hughes Service Information Notice N- 109.2 dated September 1, 1976 or later FAA-approved revisions.

  (b) If deformation, damage, or cracks are found during the inspections required by paragraph (a), before further flight, accomplish the modifications of either paragraph (c)(1) or (c)(2).

  (c) Within the next 500 hours time in service or one year whichever comes first, after the effective date of this AD:

  (1) Modify the tail boom support strut assemblies P/N 269A2015 and 269A2015-5 by replacing the aluminum end fittingswith stainless steel end fittings and attach bolts per Hughes Service Information Notice N-109.2 dated September 1, 1976 or later FAA- approved revisions, or

  (2) Replace the P/N 269A2015 strut assemblies with Hughes P/N 269A2015-9 and replace the P/N 269A2015-5 strut assemblies with Hughes P/N 269A2015-11.

  (d) For Hughes Model 269C helicopters, within the next 100 hours time in service, after the effective date of this AD, serialize the tail support strut assemblies P/N 269A2015-5 and P/N 269A2015-11 in accordance with Hughes Service Information Notice N-108 dated May 21, 1973 or later FAA-approved revisions.

  (e) Within 200 hours time in service after the effective date of this AD and thereafter at intervals not to exceed 200 hours time in service from the last inspection until the modifications of paragraph (f)(2) are accomplished, inspect the tail boom center attach fittings P/N 269A2324 and center frame aft cluster fittings P/N 269A2234 (LH) and P/N 269A2235(RH) fordamage in accordance with Hughes Service Information Notice N-82.2 dated September 1, 1976 or later FAA-approved revisions.

  (f) If damaged parts are found during the inspections required by paragraph (e), before further flight:

  (1) Replace the damaged part with a serviceable part of the same part number, or

  (2) Replace damaged tail boom center attach fittings P/N 269A2324 with Hughes P/N 269A2324-7 and replace damaged center frame aft with cluster fittings P/N 269A2234(LH) and P/N 269A2235(RH) with Hughes P/N 269A2234-3(LH) and P/N 269A2235- 3(RH).

  (g) Equivalent procedures, inspections repairs, tail boom support strut assemblies, tail boom center attach fittings or center frame aft cluster fittings may be approved by the Chief, Aircraft Engineering Division, FAA Western Region.

  (h) Special flight permits may be issued to authorize operation of helicopter to a base for accomplishment of the inspections required by this AD per FAR's 21.197 and 21.199.

This supersedes amendment 39-1587 (38 F.R. 2331), AD 73-03-01.

This amendment becomes effective September 7, 1976.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 4H12](https://openairdocs.org/tcds/4H12): Schweizer RSG LLC; names 6 of 6 models: 269B, 269D, 269A-1, 269A, 269C, 269C-1

## 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: 428 (428 by airframe model, 0 by engine model)
- Makers: Schweizer 216, Hughes 207, Schweizer RSG 5

Models with the most aircraft:

- [Schweizer 269C](https://openairdocs.org/model/schweizer-269c): 115 aircraft (airframe model)
- [Hughes 269A](https://openairdocs.org/model/hughes-269a): 97 aircraft (airframe model)
- [Schweizer 269C-1](https://openairdocs.org/model/schweizer-269c-1): 84 aircraft (airframe model)
- [Hughes 269C](https://openairdocs.org/model/hughes-269c): 74 aircraft (airframe model)
- [Hughes 269B](https://openairdocs.org/model/hughes-269b): 31 aircraft (airframe model)
- [Schweizer 269D](https://openairdocs.org/model/schweizer-269d): 12 aircraft (airframe model)
- [Hughes 269A-1](https://openairdocs.org/model/hughes-269a-1): 5 aircraft (airframe model)
- [Schweizer HUGHES 269C](https://openairdocs.org/model/schweizer-hughes-269c): 4 aircraft (airframe model)
- [Schweizer RSG 269C](https://openairdocs.org/model/schweizer-rsg-269c): 3 aircraft (airframe model)
- [Schweizer RSG 269C-1](https://openairdocs.org/model/schweizer-rsg-269c-1): 2 aircraft (airframe model)
- [Schweizer 269A](https://openairdocs.org/model/schweizer-269a): 1 aircraft (airframe model)

All 11 models: https://openairdocs.org/ad/76-18-01/models.md
Every aircraft: https://openairdocs.org/ad/76-18-01/aircraft.md

## Related documents

- [AD 2001-25-52](https://openairdocs.org/ad/2001-25-52) (historical): Strut Clevis Lug on Center Frame Aft Cluster Fitting · Schweizer 269A, 269A-1, 269B and 1 more. Effective May 8, 2002. Supersedes this AD

Its text cites no advisory circulars or STCs.

## NTSB investigations that cite this AD (3)

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

- [NTSB FTW03FA028](https://openairdocs.org/ntsb/FTW03FA028), Nov 1, 2002: Hughes 269A (N8885F), Fort Gibson, OK, destroyed, 1 fatal. Probable cause: The in-flight separation of the tail boom resulting from the failure of the fuselage to tail boom attachment fitting lugs, due to fatigue.
- [NTSB NYC01LA167](https://openairdocs.org/ntsb/NYC01LA167), Jul 9, 2001: Hughes 269A (N7028V), Clay, NY, substantial damage. Probable cause: Failure of the left aft cluster fitting due to a fatigue crack. Factors in the accident were the mechanic's failure to identify the crack at the last annual inspection, and the pilot's failure to…
- [NTSB CHI94LA013](https://openairdocs.org/ntsb/CHI94LA013), Oct 12, 1993: Hughes 269A (N7032U), Coldwater, MI, substantial damage. Probable cause: the fatigue failure of the tailboom support strut attachment lug.

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