- Effective
- December 31, 1987
- Models
- S-76A, S-76B
- Data sheet
- TCDSH1NE
- Registered aircraft
- 53 matched by model
- Product
- Aircraft · Rotorcraft
- Amendment
- 39-5778
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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| FAA DRS HTML | 19 KB | 301d1c81…96d0ec5 | FAA DRS (API key needed) |
On this page
The airworthiness directive
87-25-02 SIKORSKY AIRCRAFT: Amendment 39-5778. Applies to all Model S-76A and S-76B series helicopters through and including serial number 760350, certified in any category.
Compliance is required within the next 25 hours' time in service after the effective date of this AD, unless already accomplished.
To prevent possible loss of AC electrical power due to 26 VAC transformer single ground connection failure, provide separate ground connections for 26 VAC transformers 1 and 2.
NOTE: Sikorsky Service Bulletin No. 76-24-5, AC Electrical Power System - AC Power Transformer Ground Wires Termination-Separation of, dated October 19, 1987, constitutes an acceptable means of compliance with this requirement.
This amendment becomes effective December 31, 1987.
Affected TCDS · 1
The type certificate data sheets for the models this AD names, matched by model and maker.
Registered aircraft · 53
Registered aircraft whose airframe or engine model this AD names. Matched by model only, so check each against the AD’s applicability.
| 1980 | 2 |
|---|---|
| 1981 | 3 |
| 1983 | 1 |
| 1984 | 1 |
| 1985 | 3 |
| 1986 | 1 |
| 1987 | 3 |
| 1988 | 4 |
| 1989 | 4 |
| 1990 | 1 |
| 1991 | 3 |
| 1992 | 2 |
| 1994 | 3 |
| 1996 | 1 |
| 1997 | 2 |
19 with no year recorded