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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
Amendment 39-3249; AD 78-05-06 R2

Airworthiness Directives; GOODYEAR AEROSPACE CORPORATION: Applies to Goodyear Flexible Fuel Cells, Construction Type BTC-39


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78-05-06 GOODYEAR AEROSPACE CORPORATION: Amendment 39-3151 as amended by Amendment 39-3173 is further amended by Amendment 39-3249. Applies to Goodyear flexible fuel cells, construction type BTC-39 series manufactured between 1961 and 1971, installed on, but not necessarily limited to the following aircraft models, all series, manufactured between January 1961 and December 1973, or in which these fuel cells may have been installed as replacements after those dates.

Beech - H18, 35-B33, 35-C33, E33 and F33; 35-C33A, E33A, and F33A; E33C and F33C; P35, S35, V35, V35-TC, V35A, V35A-TC, V35B and V35B-TC; 36 and A36; 45 (T34A), B45 and D45 (T34B); D50E, J50; 95-A55, 95-B55 and 95-B55A; 95-C55, 95-C55A, D55, D55A, E55 and E55A; 95-B55B (T42A); 56TC and A56TC; 58 and 58A; 60, A60 and B60; 65, A65 and A65-8200; 70; 65-80, 65-A80, 65-A80-8800 and 65-B80; 65-88; 65-90, 65-A90; B90; C90; E90; D95A and E95A; 99, 99A, A99A and B99; 100 and A100; and any other Beechcraft airplane models or serial numbers other than those listed above on which Goodyear BTC-39 construction fuel cells have been installed as spares replacements;

Cessna - 180, 182, 185, 188 with wing tanks, 205, 206, 207, 210, 310, 320, 340, 401, 402, 411, 414, 421;

Israel Aircraft (including Aero Commander/Rockwell International) 1121 and 1123;

Piper - PA-25 and PA-31;

Rockwell International General Aviation Division - All models prefixed by 500, 560, 680, 681, 685, 690 and 720.

Compliance is required, as indicated, unless already accomplished.

To prevent a hazard to the airplane due to fuel cell leakage caused by deterioration of the cell or cell nipples, accomplish the following:

(a) Within the next 25 hours time in service after the effective date of this A.D., or within the next 30 calendar days after the effective date of this A.D., whichever occurs first, check aircraft records and manufacturer's instructions. If aircraft records or manufacturer's service data confirm that no Goodyear construction BTC-39 series cells are installed, no further action is required, except entry in the aircraft maintenance records that this check has been accomplished.

If any or all fuel cells installed are of the Goodyear BTC-39 construction series or are of unknown manufacturer or construction, conduct the checks, test and inspection specified in (b) and (c).

NOTE: Information to assist in identifying BTC-39 fuel cells, and applicable aircraft serialization, may be found in the following service instructions, or later approved revisions:

Beech Service Instruction Number 0895;

Cessna Single Engine Service Letter SE78-10;

Cessna Multi-Engine Service Letter ME78-7;

Israel Aircraft Service Bulletins CJ-17 for Model 1121, and WW-20 for Model 1123;

Piper Service Bulletin No. 591; and

Rockwell General Aviation Division Service Bulletin No. 165.

(b) Within the next 25 hours time in service after the effective date of this A.D., or within the next 30 calendar days after the effective date of this A.D., whichever occurs first, fill the fuel tanks and perform a visual check of the exterior of the aircraft wings and/or fuselage for signs of fuel leakage. Fuel wetness or color dye stains may be noted, especially in the vicinity of vents and compartment drains. Fuel stains due to overfill are not considered leakage. The visual check required by this paragraph may be performed by the pilot. Notation in the aircraft records is required by FAR 91.173(a)(2)(v).

(1) If signs of fuel leakage are observed, determine the leakage source.

(2) If leakage source is other than fuel cells or fuel cell nipples, correct in accordance with aircraft manufacturer's instructions prior to further flight.

(3) If leakage is from fuel cell or nipples, proceed with the inspection required in (c)(8) prior to further flight.

(c) Within the next 100 hours time in service after the effective date of this A.D. or within the next 180 calendar days after the effective date of this A.D., whichever occurs first, determine whether the vent nipples and fuel cell material, including the material end fittings, above the normal fuel level are intact and secure by accomplishing the fuel system integrity test and inspection as required in accordance with the applicable manufacturer's service information listed in (a) above, or as prescribed below:

(1) Position the airplane in an area of stable temperature, free from radiant heat and strong air currents, with the aircraft in approximately normal ground attitude, wings level. Install an adapter with a standpipe on the tank filler neck and another adapter and standpipe on the tank vent exit tube. The open ends of the two standpipes should terminate at approximately the same level, 12 to 14 inches above the highest part of the tank. The tank selector should be OFF.

NOTE: Some aircraft incorporate a vent system that interconnects the vent outlets of two or more tanks. Since fuel or air may flow through the interconnects from one tank to another, this characteristic must be considered in conducting the integrity test for leakage. On such aircraft it will be acceptable to conduct the integrity pressure test simultaneously on the interconnected tanks instead of on each tank individually.

CAUTION: Observe appropriate safety measures for handling fuel, fuel systems and fueled aircraft.

(2) Fill tank and standpipe and inspect for evidence of fuel leakage. Allow one or two minutes for the fuel level to stabilize.

CAUTION: Do not overpressurize tank as structural damage might occur. The 12-inch standpipe pressure specified will not exceed allowable limits for tank/fuel system pressure.

Maintain the standpipe fuel level for not less than 15 minutes after fuel level stabilization occurs, unless fuel leakage is observed sooner. Fuel tank or system leakage may also be revealed by a reduction in the height of fuel in the standpipe.

(3) If the standpipe fuel level remains stabilized for 15 minutes, and if there is no evidence of fuel leakage, the test may be discontinued for that tank.

(4) Repeat the test of (c)(1) and (c)(2) for each tank that incorporates a cell of BTC-39 or a tank cell of unknown type construction.

(5) If no leaks are observed, the test may be terminated. The fuel system should be returned to normal flight configuration, and the aircraft may be returned to service. Make notation in the aircraft records in accordance with FAR 91.

(6) If there is evidence of fuel leakage, determine the source of the leak.

(7) Repair fuel system leaks, other than fuel cell or nipple leaks, in accordance with the appropriate aircraft manufacturer's instructions.

(8) If evidence of fuel cell or nipple leakage is observed, conduct the following inspection of each cell and all nipples for the source of the leak.

(i) Drain fuel tanks and remove access covers or plates.

(ii) After thorough purging of the tank interiors to remove fuel vapors, use explosion-proof light and mirror and visually inspect the interior and exterior (where accessible) of each cell suspected of leakage for cracking, peeling or other signs of deterioration.

(iii) Inspect the tank retaining fasteners and determine that they are properly positioned and fastened.

(iv) Inspect vent, drain and all nipples. These may be inspected by the fingernail test to give an indication of the condition of the nipple. The fingernail test consists of using the fingernail to attempt to scrape the compound off the nipple fitting. If the compound has not degraded, the fingernail will glide across the surface without damage to the compound. If an unsatisfactory condition exists, the fingernail will tend to dig into the compound. The deteriorated compound will have a consistency of either art gum or chewing gum.

(v) Remove any fuel cell found leaking or with deteriorated nipples. BTC-39 series type cells which have been removed are not repairable, and must not be installed as a serviceable cell in an aircraft. Other type cell construction may be repaired in accordance with the applicable manufacturer's instructions by a person authorized in FAR Part 43.

(vi) Install serviceable fuel cells, reconnect fuel cell and fuel system, and access covers, and functionally pressure check fuel system in accordance with aircraft manufacturer's service data or item (c).

(d) Repeat the integrity pressure test and inspection required in (c) at intervals not to exceed 12 months until all BTC-39 type construction fuel cells or cells of unknown construction have been replaced.

(e) An equivalent means of compliance with this A.D. is to comply with the aircraft manufacturer's instructions listed in (a), provided that the visual check is accomplished at the compliance time required in (b) and that the inspection and tests are conducted at the intervals specified by (c) and (d). Any other method must be approved by the Chief, Engineering and Manufacturing Branch, Federal Aviation Administration, Southern Region.

(f) Upon request of the operator, an FAA maintenance inspector may adjust the inspection interval specified in (c) and the repetitive inspection interval specified in (d) of this A.D. to permit compliance at an established inspection period of the operator if the request contains substantiating data to justify the increase for that operator. The time for conducting the checks required by (a) and (b) may not be adjusted.

Amendment 39-3151 became effective March 17, 1978.

Amendment 39-3173 became effective April 10, 1978.

This amendment 39-3249 becomes effective June 30, 1978.



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