AD 62-10-02 ACTIVE

62-10-02 CURTISS-WRIGHT: Amdt. 427 Part 507 Federal Register April 20, 1962. Applies to all C-46 Series aircraft except the following: Aircraft listed on Aircraft Specification 2A5, C-46R aircraft listed on Aircraft Specification 3A2, Aircraft certificated under STC SA4- 33, Aircraft certificated under STC SA2-422, and any other aircraft meeting all of the fire protection requirements of SR-406C.

Compliance required within the next 500 hours of time in service after May 22, 1962.

To correct the fire protection deficiencies on the C-46 Series aircraft, the following is required:

(a) To prevent fire originating in the engine sections from burning into the wheel well area, accomplish the following or FAA approved equivalent unless already accomplished:

(1) Cover the landing gear doors with an 0.015 stainless steel sheet from the forward edge of the doors aft to approximately Station 145 (approximately 55 inches).

(2) Cover the fixed portion of the lowerwheel well skin fore and aft between the firewall and the forward edge of the landing gear doors, peripherally between the wheel well door hinge lines, with an 0.015 stainless steel sheet.

(3) Cover the sides of the nacelle in the area of the exhaust impingement with an 0.015 stainless steel rectangular sheet approximately 20 inches by 40 inches with the lower, long side boundary along the landing gear door hinge line and the forward, short side even with the forward edge of the existing nacelle skin at the firewall.

Attach all of the above steel sheets with monel or steel fasteners.

(b) In order to generally improve the powerplant fire protection in C-46 Series aircraft, accomplish the following or FAA approved equivalent unless already accomplished.

(1) SHUT-OFF VALVES. Install fluid shut-off valves which may be opened and closed in flight aft of the firewall in all fuel, oil, and hydraulic lines. USAF Technical Order 01-25LA-190 covers this same subject. Ifpropeller or carburetor anti-icing systems are employed and use alcohol or other flammable fluids as the anti-icing medium, the systems described in USAF T.O. AN 01-25LA-2, pages 458-464, are satisfactory except that shut-off valves or a selector valve which can be opened and closed in flight must be provided aft of the firewall to shut off the flow to either engine. The system shall be such as to shut off the pump automatically, or otherwise guard against hazardous pressures, when the flow to both nacelles is stopped. (No shut-off valve will be required for the feathering pump oil lines - see (b)(3)).

(2) ENGINE FIREWALLS. Engine firewalls must be rendered fireproof by adequately sealing all openings such as the filtered air duct opening, the oil cooler control rod and filtered air control rod openings, other power plant control openings, holes through the firewall for electric conduits, and any other firewall openings. All attachments through the firewall utilized in renderingthe firewall fireproof shall be monel or steel attachments.

(3) PROPELLER FEATHERING PUMP INSTALLATION. The portion of the propeller feathering oil line forward of the firewall between the firewall and the pump shall be of steel or other fireproof material. The line between the pump and governor shall be of fire resistant material with coupled hose assemblies, meeting the requirements of TSO-C42, used in any flexible connections. Electrical conduit for the pump motor and other electrical components forward of the firewall which are essential for propeller feathering shall be fire resistant or protected in a manner to render them fire resistant. Wire conforming to MIL-C-25038 is considered fire resistant. The feathering pump can be considered an adequate means of shutting off the flow of oil in the feathering line.

(4) FIRE DETECTORS. The Fenwal continuous type fire detectors (non-repeatable, fusible-alloy, obsoleted in 1950), which were originally provided, must be removed and replaced with unit or continuous type fire detectors conforming with FAA Technical Standard Order, TSO-C11 or FAA approved equivalent. Such detectors shall also meet the requirements specified in subparagraphs (i) through (vi). If unit type detectors are used, they shall be spaced as specified in subparagraphs (i) and (ii) and continuous type detectors, if used, shall be so installed as to provide the same coverage.

(i) Engine nacelles: Fire detectors, spaced not over 7 inches apart, shall be installed on the lower half of the forward side of the firewall at its outer periphery, and along the horizontal diameter. Also, fire detectors shall be located so as to be in the air egress pattern for any other openings in the engine or accessory cowling.

(ii) Engine mount ring and oil cooler supports: Additional fire detectors, spaced not over 18 inches apart, shall be provided for the upper two-thirds of the engine mount ring. Also, a fire detector shall be installedon each oil cooler support approximately 2 or 3 inches above the oil cooler.

(iii) Warning light covers: Fire-warning-light covers or shutters, which are capable of dimming or shutting off the light entirely, must be removed.

(iv) Means shall be provided to permit the crew to check in flight the functioning of the electric circuit associated with the fire detection and fire warning systems.

(v) Wiring and other components of the fire detection system which are located in the engine and accessory sections shall be of fire resistant construction. (See (b)(2) for firewall attachments.)

(vi) Aural fire warning means, along with fire warning lights, shall be installed to indicate the presence of fire in either engine nacelle.

(5) ENGINE COMPARTMENT LINES. The following lines carrying inflammable fluids or vapors in the engine compartment shall be fire resistant, and items (a) through (g), inclusive, shall also have fireproof firewall fittings. Flexible connections in lines attached to the engine or subject to relative motion or pressure shall employ fire resistant coupled hose assemblies: (a) carburetors bled back lines, (b) cabin heater fuel lines, (c) oil dilution lines, (d) fuel pressure transmitter lines, (e) oil pressure transmitter lines, (f) manifold pressure lines, (g) all other hydraulic oil lines, (h) all engine fuel lines, (i) engine primer lines, (j) engine breather lines, (k) engine supercharger drain lines, (l) oil separator return lines, (m) vacuum system pressure lines, (n) all main oil lines, (o) engine oil cooler lines, (p) hydraulic pump drain lines, (q) exhaust collector drain lines, (r) oil tank vent lines, (s) fuel pump drain lines.

Flexible hose assemblies for those lines noted above shall conform to TSO-C53 Type "C". Metal tubing, hose, and clamp type plumbing utilized in those lines noted above shall consist of steel tubing and fire resistant hose. Aeroquip 624 fire sleeve, or equivalent, may be utilized to render nonfire resistant hose (for the hose, steel tube, and clamp type plumbing) fire resistant. Aluminum firewall fittings, sizes 1-inch and larger, will be acceptable as fireproof fittings.

(6) AIRPLANE FLIGHT MANUAL. Appropriate changes to the airplane flight manual shall be prepared to cover emergency procedures associated with the above changes.

(c) Upon request of the operator, an FAA maintenance inspector, subject to prior approval of the Chief, Engineering and Manufacturing Branch, FAA Southern Region, may adjust the compliance times specified in this AD if the request contains substantiating data to justify the increase for such operator.

This directive effective May 22, 1962.

Revised June 30, 1962.

Revised August 7, 1962.