# AD 66-13-03: Inverter Ground System

- Type: Airworthiness directive
- Status: Current
- Products: Maryland Air Industries F-27, F-27A, F-27B, F-27F, F-27G, F-27J and F-27M
- Effective: June 11, 1966
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Large airplane
- Amendment: 39-232
- Registered aircraft: 1 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/ECE2EEB7F19BFEF28625698400724834.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/66-13-03

## The airworthiness directive

66-13-03 FAIRCHILD: Amdt. 39-232 Part 39 Federal Register May 12, 1966. Applies to Model F-27 Series Airplanes.

Compliance required within the next 350 hours' time in service after the effective date of this AD, unless already accomplished.

To prevent failure of both inverters and resulting loss of essential load circuits due to a failure of a common ground, accomplish the following:

  (a) For airplanes with inverter ground circuits conforming to Fairchild Drawing 27-740027 including EAI No. 1, or that have been modified in accordance with Fairchild Service Bulletin No. 34-4, dated November 5, 1959, modify the inverter ground circuit in accordance with the "Accomplishment Instructions" of Fairchild Service Bulletin 34-9, dated December 16, 1965, or later FAA-approved revision, or an FAA-approved equivalent.

  (b) For airplanes with inverter ground circuits conforming to Fairchild Drawing 27-740027 not including EAI No. 1, and that have not been modified in accordance with Fairchild Service Bulletin No. 34-4, dated November 5, 1959, modify the inverter ground circuit in accordance with Fairchild Service Bulletins 34-4, dated November 5, 1959, or 34-9, dated December 16, 1965, or later FAA-approved revisions, or an FAA-approved equivalent.

  (c) Upon request of the operator an FAA maintenance inspector, subject to the prior approval of the Chief, Engineering and Manufacturing Branch, FAA Eastern Region may adjust the compliance time specified in this AD to permit compliance at an established inspection period of the operator, if the request contains substantiating data to justify the increase for that operator.

This directive effective June 11, 1966.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 7A1](https://openairdocs.org/tcds/7A1): Maryland Air Industries Inc.; names 7 of 12 models: F-27, F-27A, F-27M, F-27J, F-27F, F-27B, F-27G

## 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: 1 (1 by airframe model, 0 by engine model)
- Makers: Fairchild 1

Models with the most aircraft:

- [Fairchild F-27F](https://openairdocs.org/model/fairchild-f-27f): 1 aircraft (airframe model)

All 1 models: https://openairdocs.org/ad/66-13-03/models.md
Every aircraft: https://openairdocs.org/ad/66-13-03/aircraft.md

Its text cites no advisory circulars or STCs.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.