# AD 62-27-05: Electrical Distribution 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: January 29, 1963
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Large airplane
- Registered aircraft: 1 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/CD847DCA455A94DC8625698400724292.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/62-27-05

## The airworthiness directive

62-27-05 FAIRCHILD: Amdt. 524 Part 507 Federal Register December 28, 1962. Applies to Model F-27 Aircraft Serial Numbers 2 to 95 Inclusive.

Compliance required within the next 1,000 hours' time in service after the effective date of this AD.

In order to preclude the loss of DC power to the primary DC bus in the event of failure of the forward primary bus relay, and the loss of AC power to certain engine instruments in the event of loss of the 115/26V instrument transformer, the following, or an equivalent approved by Chief, Engineering and Manufacturing Branch, FAA Eastern Region, New York, shall be accomplished:

  (a) Modify the DC electric distribution system to provide an alternate means of connecting the primary bus to the No. 2 electrical panel battery-generator feeder bus by installing one auxiliary forward primary bus relay, Cutler Hammer P/N 6041H172 in parallel with the existing forward primary bus relay. The control circuit for this auxiliary relay shall be made independent of the control circuit for the existing primary bus relay by connecting it to the flight emergency bus through an added 5-ampere circuit breaker and through a separate pair of contacts in the load monitor switch, P/N MS35059-22.

  (b) Modify the AC electric distribution system to provide an alternate means of supplying 26V electric power to the AC engine instruments by installing one Eclipse-Pioneer instrument transformer type DW-73-A1 and one selector switch P/N MS 35059-23 which will provide for selection of either one of the two instrument transformers.

(Fairchild Service Bulletin 24-9 Revision No. 1, dated June 11, 1962, covers this same subject.)

This directive effective January 29, 1963.

## 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/62-27-05/models.md
Every aircraft: https://openairdocs.org/ad/62-27-05/aircraft.md

Its text cites no advisory circulars or STCs.

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