47-42-03 DOUGLAS: (Was Mandatory Note 22 of AD-762-7.) Applies to C-54 and DC-4 Aircraft. \n\nAll the provisions of items A through O apply to airplanes used for carrying passengers under the provisions of Parts 41, 42 and 61 of the Civil Air Regulations. On these airplanes the changes are to be accomplished not later than November 1, 1948. \n\nOnly items A, (12), A (15), C, D, F, J, K (1), K (2), L, M, O (2), O (4), O (5), and O (7) apply to airplanes other than those indicated above. On these airplanes the changes are to be accomplished not later than the first engine change after November 1, 1948. \n\nAs a result of investigation of powerplant fires which have occurred in this type aircraft, the following changes are to be accomplished: \n\nA.\t1.\tSeal all cracks and baffles in oil cooler fairing and provide additional drain holes. \n\t2.\tRework cowl tail pipe shroud to eliminate all cracks and gaps and seal shroud to cowl panel joint. \n\t3.\tSeal inner ring corners at oil cooler joints. \n\t4.\tReinforce exhaust shroud to prevent damage when used as a step and seal same. \n\t5.\tProvide accessory compartment vent opening in oil cooler fairing panel. \n\t6.\tSeal joints between all engine accessory sections cowling panels to prevent leakage of flame into accessory section. \n\t7.\tEliminate engine accessory compartment vent opening in the side accessory section cowl panel. \n\t8.\tSeal pressure transmitter and fire warning switch holes on firewall. \n\t9.\tClose gap between aft oil cooler fairing and nacelle skin aft of firewall. \n\t10.\tRework the hydraulic suction line connecting to the shutoff valve aft of the firewall to prevent failure at fittings due to rigidity of the line. \n\t11.\tRelocate the hydraulic pressure and automatic pilot lines to move them farther away from the exhaust shroud. \n\t12.\tAdd a check valve in the automatic pilot delivery line behind the firewall. \n\t15.\tChange the nacelle firewall miscellaneous line connector assembly on the right side of thefirewall from dural to steel. \n\t16.\tChange carburetor air scoop adapter sleeve to provide a tight and flexible connection. \n\t17.\tReplace exhaust stack nuts with special long-type nuts, extending past stud ends, on exhaust pipe attachments to engine and safety wire the nuts in place. \n\t18.\tChange nuts and bolts used on the four-bolt flanges at the top of the exhaust collector ring to stainless steel. \n\t19.\tSeal main landing gear door hinges on inboard nacelles. \n\t20.\tInstall means to prevent exhaust nipples from telescoping and pulling out of cylinder exhaust ports, in the event of exhaust port stud failure. (Douglas clamp assembly P/N 4244017 may be used.) \n\n(Douglas Service Bulletin C-54-250 covers the above items respectively. Items 13 and 14 of that Bulletin are not required by this Note.) \n\nB.\tRework forward edge of exhaust shroud to eliminate gaps leading into engine accessory section. \n\n(Part I, Douglas Service Bulletin C-54-234, covers this same subject.) \n\nC.\tAdd two fire detectors on forward face of firewall in vicinity of shutoff valve location. \n\n(Douglas Service Bulletin No. C-54-252 covers this same subject.) \n\nD.\tRelocate engine primer solenoid to prevent fuel from running into electrical junction box on rear face of firewall. \n\n(Item 12, Douglas Service Bulletin DC-4 No. 66, covers this same subject.) \n\nE.\tInstall extended tail pipes on exhaust collectors. \n\n(Douglas Service Bulletin C-54-289 covers this same subject.) \n\nNOTE: Some of the above-mentioned changes were accomplished at the time Army or Navy airplanes were converted for civil certification. However, it will be necessary to check for compliance, in order to insure that items A to E, inclusive, are complied with. \n\nF.\tImprove the seal at the point where the top of the oil radiator duct fits against the cutout in the bottom of the accessories section diaphragm. \n\n(Part 1 of Douglas Service Bulletin DC-4 No. 49 covers this same subject.) \n\nG.\tRevise sealingof engine section drain line support adjacent to oil cooler shroud by installing a drain manifold. \n\n(Part B of Douglas Service Bulletin DC-4 No. 66 covers this same subject.) \n\nH.\tReplace dural oil inlet elbow on oil cooler with new type steel elbow. \n\n(Part F, 9 of Douglas Service Bulletin DC-4 No. 66 covers this same subject.) \n\nI.\tImprove sealing of engine accessories section diaphragm at the four cutouts for the exhaust collector ring supports. \n\n(Part 2 of Douglas Service Bulletin DC-4 No. 49 covers this same subject.) \n\nJ.\tReplace micarta fairleads with fairleads of fire resistant material for propeller governor and carburetor air preheat control cables on inner ring and for all engine control cables on firewall. \n\n(Douglas Service Bulletin DC-4 No. 55 covers this same subject.) \n\nK.\t1.\tInstall seven fire-warning detectors in zone 1, (engine power section) on the cowl flap ring brackets and install separate set of warning lights in the cockpit for each engine.2.\tAdd an additional fire warning detector in zone 2, (engine accessories section) on top of the oil cooler housing at approximately the center of the section. \n\n(Douglas Service Bulletin DC-4 No. 57 covers the above two items.) \n\nL.\tReplace open relays in junction box behind firewall with sealed relays and provide a drain for the junction box. \n\n(Douglas Service Bulletin DC-4 No. 61 covers this same subject.) \n\nM.\tAttach nacelle junction box cover plate on forward face of firewall directly to firewall rather than to the junction box. \n\n(Douglas Service Bulletin DC-4 No. 65 covers this same subject.) \n\nN.\tInspect and seal all holes in the inner ring around the carburetor air preheat control and install fire resistant fairlead in retainer. \n\n(Douglas Service Bulletin DC-4 No. 55 covers this same subject in part.) \n\nO.\t1.\tInspect and rework if necessary, inner ring cutouts for cowl flap actuating bellcranks to provide metal-to-metal contact between inner ring and cowlflap bellcrank bracket on aft side of inner ring. Dimple inner ring to accomplish metal-to-metal contact, or fill gap with washers made from Johns Manville No. 96 wire woven asbestos sheet impregnated with neoprene. \n\n\t2.\tInspect and rework diaphragm, inner ring and firewall for excess holes, gaps and rubber grommets. Close and seal all holes and gaps, and install fireproof grommets or equivalent. \n\n\t3.\tInspect and seal, with Johns Manville No. 96 or equivalent, gaps that may exist where the carburetor airscoop casting passes through the accessory section inner ring. \n\n\t4.\tInspect and seal with Johns Manville No. 96 split seal or equivalent the hole where the engine oil line (from the intermediate rear section to the main oil sump) passes through the plate in the accessory section diaphragm at the bottom of the engine. \n\n\t5.\tInspect and seal with Johns Manville No. 96 or equivalent any gaps that may exist where the plate mentioned in item 4, above, mates with the outer section of the accessory section diaphragm. \n\n\t6.\tInspect and seal gaps existing between the diaphragm and the three engine crank case bosses. The magneto vent lines pass through the gaps around two of these bosses; the manifold pressure takeoff line at right top of engine being the third.\n \n\t7.\tProvide a fluid shutoff means at a point behind the firewall in the line leading from the oil tank to the feathering pump on airplanes having the feathering pump located on the engine side of the firewall. This may be accomplished by a shutoff valve tied into the present shutoff valve linkage aft of the firewall, or a flapper type check valve. \n\nNOTE: Items 0-1 through 0-7 are to be developed and accomplished by the operators affected, since Douglas has not prepared Service Bulletins to cover these changes.