# AD 59-18-05: Combustion Heater Modification

- Type: Airworthiness directive
- Status: Current
- Products: Maryland Air Industries F-27, F-27A, F-27B, F-27F, F-27G, F-27J and F-27M
- Superseded by: Nothing supersedes this AD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/22C8FC496593ACF18625698400723F0D.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/59-18-05

## The airworthiness directive

59-18-05 FAIRCHILD: Applies to all F-27 Series aircraft equipped with the heater system.

Compliance required not later than October 15, 1959.

  (a) In order to provide drainage of possible leakage at the heater fuel line fittings, remove three shroud assemblies, P/N 27-774575-1, attached to tube connections at top of heater fuel control, P/N 43C80, and heater P/N 49C65. Modify shroud assemblies by punching one (1) 1/8-inch diameter hole in side of shroud 1 13/64 inches from top.

  (b) Remove fuel control drain tube assembly, P/N 27-774554-11 or -51, whichever installed.

  (c) On airplanes Nos. 1 to 6 inclusive, drill 5/8-inch diameter hole in bottom fuselage skin between stringers Nos. 102 and 103, 2 1/2 inches aft of Station 731, and install AN 931-6-10 grommet removed from former location of drain line. Install flush skin patch over former drain hole location in accordance with Chapter 51-7 of F-27 Structural Repair Manual.

  (d) On all affected airplanes, install new drain tube assembly, P/N 27-774750-11 in place of 27-774554-11 or -51.

  (e) Install modified shroud assemblies, using three each new half clamp assemblies, P/N 27-774749-11, half clamp P/N 27-774749-3, bolt P/N AN 3-3A, and nuts P/N MS 20365-1032.

  (f) Install one each new hose, P/N 27-774094-3 and -5 between heater fuel control shrouds and drain tube and P/N 27-774094-7 between heater shroud and drain tube, using six new clamps, P/N AN 737RM22.

  (g) Install two new plates, P/N 27-774749-9, on the heater fuel control unit, and four new clamps, P/N AN 742-8, two on the plates at the fuel control unit to support 27-774094-3 and -5 hose and two on the flanges of the fuselage former at Stations 730 and 731 to support 27-774094-7 hose. Use four each new screws P/N AN 525-10R6, and nuts P/N MS 20365-1032.

(Fairchild F-27 Service Bulletin No. 21-49 dated June 12, 1959, covers this same subject.)

Compliance with AD 59-12-01 no longer required after compliance with this directive.

## 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/59-18-05/models.md
Every aircraft: https://openairdocs.org/ad/59-18-05/aircraft.md

Its text cites no advisory circulars or STCs.

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