- Effective
- November 30, 1978
- Models
- S-58BT, S-58DT, S-58ET, S-58FT, S-58HT, S-58JT
- Data sheet
- TCDS1H11
- Registered aircraft
- 10 matched by model
- Product
- Aircraft · Rotorcraft
- Amendment
- 39-3322
Unofficial copy of the text in the FAA’s Dynamic Regulatory System. The FAA’s own copy is the authoritative one. DRS record last changed May 30, 2024.
Copies of the files this page was built from, with their SHA-256. Retrieved October 18, 2026.
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On this page
The airworthiness directive
78-21-05 SIKORSKY AIRCRAFT: Amendment 39-3322. Applies to S-58BT, S-58DT, S-58ET, S-58FT, S-58HT, and S-58JT helicopters certificated in all categories.
To prevent possible tail rotor instability accomplish the following:
Within 200 hours time in service or three months, whichever comes first, after the effective date of this AD, unless already accomplished, complete the following:
(a) Install improved abrasion strips, Sikorsky Modification Kit 58070-10008-011, on tail rotor blades, P/Ns S1615-30100-3, -4, -7, -10, -11, -15, -16, -041, -042, and -043. This modification is covered by Sikorsky Service Bulletin No. 58B15-18.
(b) Install Sikorsky control rod assembly, P/N 58400-64010-101.
This modification is covered by Sikorsky Service Bulletin No. 58B40-5.
This amendment becomes effective November 30, 1978.
Affected TCDS · 1
The type certificate data sheets for the models this AD names, matched by model and maker.
Registered aircraft · 10
Registered aircraft whose airframe or engine model this AD names. Matched by model only, so check each against the AD’s applicability.
| 1956 | 1 |
|---|---|
| 1957 | 2 |
| 1958 | 2 |
| 1959 | 1 |
| 1962 | 3 |
1 with no year recorded
By model
Aircraft
NTSB investigations that cite this AD · 1
Their narratives or probable cause name AD 78-21-05, often to say whether the aircraft complied with it.