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76-08-05: 76-08-05 DEHAVILLAND AIRCRAFT of CANADA, LTD: Amendment 39-2585.
1. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 2 thru 15, 17, 22, 23, 26, 27 and 28, certificated in all categories, but not altered in accordance with DeHavilland Modification No. 3/341.
Compliance required within the next 100 hours in service after the effective date of this AD.
To provide a more positive current return path from the fuel booster pump motor so as to eliminate the possibility of a fire hazard due to overheating of the pump, install cable jumper in accordance with "Modification Procedure" paragraph of DeHavilland Technical News Sheet, Series Otter, No. 22, or an approved equivalent alteration.
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2. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 2 thru 15, 17 thru 42, 44, 45, 46, 52 thru 65 and 67 thru 70, certificated in all categories, but not altered in accordance with DeHavilland Modification No. 3/558.Compliance required within the next 100 hours in service after the effective date of this AD.
To provide a greater margin of safety in the event of an engine compartment fire, replace breather pipe assembly part No. C3-E-3-5 and drain box part No. C3-L-11 with breather pipe assembly part No. C3-E-3-22 and drain box part No. C3-L-21 in accordance with paragraph "DATA" of DeHavilland Engineering Bulletin, Series "O", No. 5 or an approved equivalent alteration.
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3. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 2 thru 96 except 16, 77, 78, 79, 91, 93 and 94, certificated in all categories, but not altered in accordance with DeHavilland Modification No. 3/680.
Compliance required within the next 100 hours in service after the effective date of this AD.
To prevent failure of the left hand upper exhaust pipe, part No. C3-EE-6/B, at a point immediately below the existing clamp bracket, install two additionalclamps part No. C3-EE-18 and support strut, part No. C3-EE-42, on exhaust pipes in accordance with paragraph 5. "PROCEDURE" of DeHavilland Engineering Bulletin, Series "O", No. 19, or an approved equivalent alteration.
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4. Applies to all DHC-3 (U-1A) Airplanes prior to Serial Number 390 except Serial Number 320, certificated in all categories, but not altered in accordance with DeHavilland Modification No. 3/865.
Compliance required within the next 100 hours in service after the effective date of this AD.
To reduce the possibility of in-flight failure of the oil delivery line from the Constant Speed Unit and resultant loss of engine oil, install an improved oil line assembly installation in accordance with paragraph "PROCEDURE" of DeHavilland Engineering Bulletin, Series "O", No. 68, Issue 3, or an approved equivalent alteration.
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5. Appliesto all DHC-3 (U-1A) Airplanes prior to Serial Number 435, certificated in all categories, but not altered in accordance with DeHavilland Modification No. 3/888.
Compliance required at next engine removal but not later than the next 100 hours in service after the effective date of this AD.
To provide fireproof integrity of the engine firewall, replace aluminum rivets with monel rivets and install sixteen additional steel bolts in accordance with paragraph "PROCEDURE" of DeHavilland Engineering Bulletin, Series "O", No. 72, or an approved equivalent alteration.
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6. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 2 thru 15 and 17, certificated in all categories.
Compliance required as indicated:
a. Within 50 hours in service after the effective date of this AD, unless already accomplished, inspect the fuselage former cap strips at Station 153.77 and 174.22 on left and right sides of the aircraft, in accordance with the procedure described in DeHavilland Aircraft, Ltd. Technical News Sheet, Series Otter No. 24, Modification Data, Part "A", or an approved equivalent inspection procedure.
b. If additional rivets are determined necessary, after the inspection in paragraph (a) is completed, accomplish the installation in accordance with the above DeHavilland Modification Data, Part "B", or an approved equivalent alteration.
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7. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 2 thru 15, 17, 22, 23 and 25 thru 28, certification in all categories.
Compliance required within the next 25 hours in service after the effective date of this AD, unless already accomplished.
To ensure adequate locking of the rear cargo door, install straps, P/N C3-FF-351, or C3- FF-361-5 in accordance with the Modification Procedures and Sequence of Operation described in DeHavilland Aircraft, Ltd. Technical News Sheet, SeriesOtter No. 17, or install an approved equivalent alteration.
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8. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 2 thru 15, 17, 18, 20 thru 23, and 25 thru 31, certificated in all categories, but not altered in accordance with DeHavilland Modification No. 3/349.
Compliance required within the next 25 hours in service after the effective date of this AD.
To prevent the cargo doors from being inadvertently opened, install handle guards, P/N C3-FS-524, on right and left side cargo door in accordance with paragraph "MODIFICATION DATA" of DeHavilland Aircraft, Ltd. Technical News Sheet, Series Otter, No. 21, or install an approved equivalent alteration
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9. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 3 thru 17 except 16, certificated in all categories, but not altered in accordance with DeHavilland Modification No. 3/193.
Compliance required within the next 100 hours in service after the effective date of this AD. To stiffen skin panels around the access holes located in the rear of the fuselage, add required stiffeners in accordance with the "Modification Procedure" described in DeHavilland Aircraft of Canada, Ltd. Technical News Sheet, Series Otter, No. 9, or an approved equivalent alteration.
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10. Applies to DHC-3 (U-1A) Airplanes with Serial Numbers 3 thru 15, certificated in all categories, but not altered in accordance with DeHavilland Modification No. 3/149.
Compliance required within the next 25 hours in service, unless already accomplished. To preclude the failure of existing attachments, replace 3/16 rivets with AN174-6 bolts for the attachment of the Rudder Quadrant Support Bracket, P/N C3-FS-169, in accordance with the "Modification Procedure" described in DeHavilland Aircraft, Ltd. Technical News Sheet, Series Otter No. 3, or an approved equivalent alteration.
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11. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 2 thru 15, certificated in all categories, but not altered in accordance with DeHavilland Modification No. 3/203.
Compliance required within 50 hours in service. To prevent rudder control reversal, install safety block, P/N C3-FS-504, for rudder pedal linkages, in accordance with the "Modification Procedure" described in DeHavilland Aircraft, Ltd. Technical News Sheet, Series Otter, No. 4, or an approved equivalent alteration.
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12. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 2 thru 208, except 135, 171, 176, 190, 193, 195, 197, 202 thru 204 and 207, certificated in all categories, but not altered in accordance with DeHavilland Modification 3/699.
Compliance required within 100 hours in service after the effective date of this AD. Replace the present lower rudder hinge assembly, P/N C3-TR-14 in accordance with paragraph 6 "PROCEDURE" in DeHavilland Aircraft, Ltd. Engineering Bulletin, Series "O", No. 28, or an approved equivalent alteration.
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13. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 2 thru 177 except 16 and 67, certificated in all categories, but not altered in accordance with DeHavilland Modification No. 3/670.
Compliance required within 50 hours in service after the effective date of this AD. To prevent structural damage due to ground handling, reinforce the fuselage structure on left and right side, at the horizontal stabilizer attachment brackets, Station 427, in accordance with paragraph 6. "PROCEDURE" in DeHavilland Engineering Bulletin, Series "O", No. 29, or an approved equivalent alteration.
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14. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 1 thru 300 and 324, certificated in all categories.
Compliance required within the next 25 hours in service after the effective date of this AD, unless already accomplished. To prevent failure of the rudder control system, inspect Rudder Control Bellcrank Assemblies, P/Ns C3-CF-15 and CS-CF-15-7, for cracks using a dye penetrant method with a glass of at least 10 power, or using an approved equivalent inspection. For area of assemblies to be inspected refer to DeHavilland Aircraft of Canada, Ltd. Engineering Bulletin, Series "O", No. 63, Page 2, Figure 1.
Replace cracked parts before further flight with parts of the same part number or approved equivalent parts.
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15. Applies to all DHC-3 (U-1A) Airplanes operating on skis or wheel-skis, certificated in all categories.
Compliance required, unless already accomplished, each time skis or wheel-skis are installed, or, within the next 50 hours in service, if the skis or wheel-skis arealready installed, and thereafter at intervals not to exceed 250 hours in service since the last inspection while operating on skis or wheel-skis.
To detect cracks and preclude failures of the bolts attaching the upper end of the axle and compression struts to the fuselage, accomplish the following:
a. Inspect in accordance with paragraph (1), (2) and (3) under the sub-title "Procedure" in DeHavilland Service Bulletin No. 3/12, Issue 2, or in accordance with an approved equivalent inspection.
b. Replace cracked bolts, P/N C3U72-3 (axle strut) and P/N C3U142-5 with new bolts of the same part numbers, or approved equivalent bolts.
c. If bolts are undamaged, reinstall and grease in accordance with DHC-3 Maintenance Manual Lubrication Instruction.
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16. Applies to DHC-3 (U-1A) Amphibian Airplanes Serial Numbers 2 thru 410 only, certificated in all categories, but not altered in accordance with DeHavilland Modification 3/837.
Compliance required within the next 100 hours in service after the effective date of this AD. In order to preclude damage due to landing on wheels, reinforce fuselage, forward and aft of joint, Station 264.00, in accordance with the "PROCEDURE" described in DeHavilland Aircraft, Ltd. Engineering Bulletin, Series "O", No. 57, Issue 2, or an approved equivalent alteration.
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17. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 2 thru 253, certificated in all categories.
Compliance required within the next 25 hours in service after the effective date of this AD, unless already accomplished. Replace the two ESNA clinch nuts, P/N 22-NC6-048, holding the fork attachment fitting, P/N C3T15-5, to the tailplane with two ESNA clinch nuts, P/N 22- NC4-048, in accordance with paragraph 6. "PROCEDURE" in DeHavilland Aircraft of Canada, Ltd. Engineering Bulletin, Series "O", No. 47, Issue 2, orwith an approved equivalent alteration.
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18. Applies to DHC-3 (U-1A) Airplanes, certificated in all categories, but not altered in accordance with DeHavilland Modification No. 3/909.
To prevent possible adverse airplane flutter effects from the flap interconnect tab on the elevator accomplish the following:
1. Compliance required within the next 50 hours in service after the effective date of this AD.
a. Attach the following operating limitation placard near the airspeed indicator in full view of the pilot:
"VNE SPEED SHALL NOT EXCEED 150 MPH (130 KNOTS) CAS."
b. Conduct an inspection of the items listed in DeHavilland Aircraft of Canada, Ltd. Service Bulletin, Series Otter, No. 3/4, or an approved equivalent inspection.
2. Within three months after the effective date of this Airworthiness Directive accomplish either:
a. An alteration of the red radial VNE line and the cautionary yellow arc of the airspeed indicator to reflect the VNE speed = 150 MPH (130 Knots) CAS, in accordance with an approved alteration; or
b. A modification of the elevator tab horn in accordance with DeHavilland Aircraft of Canada, Ltd. Service Bulletin, Series Otter, No. 3/6, or an approved equivalent modification.
3. When either alteration in paragraph 2 of this AD item is incorporated the placard in paragraph 1(a) can be removed.
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19. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 1 thru 356, certificated in all categories.
1. Compliance required within the next 50 hours in service, after the effective date of this AD, unless already accomplished. Perform the following in accordance with the "PROCEDURE" in DeHavilland Aircraft of Canada, Ltd. Engineering Bulletin, Series "O", No. 66, or an approved equivalent procedure.
a. Visually inspect the wing strut spars P/N C3W101-4, on wing struts P/N C3W101-9, at both ends for cracks.
b. If a crack is found at either end of the wing strut spar, which is less than 0.75 inch in length and does not enter a rivet hole, repair the spar prior to next flight, as in paragraph 3 of the above Bulletin, or an approved equivalent repair.
c. If a crack is found longer than 0.75 inch in a strut spar, or a crack enters a rivet hole, prior to next flight, replace with a part of the same part number or an approved equivalent part, or repair in accordance with an approved procedure.
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20. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 2 thru 155, certificated in all categories, but not altered in accordance with DeHavilland Modification No. 3/735.
Compliance required within the next 100 hours in service after the effective date of this AD.
To prevent inadvertent damage to the horizontal tail front hinge supporting structure, install "NO PUSH" signs on the leading edges of the left and right horizontal tail and elevator horns as indicated in paragraph 5 "PROCEDURE" of DeHavilland Aircraft of Canada, Ltd. Engineering Bulletin, Series "O", No. 32, or an approved equivalent alteration.
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21. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 2 thru 26, certificated in all categories, but not altered in accordance with DeHavilland Modification No. 3/721.
Compliance required at the next 50 hours in service after the effective date of this AD. To prevent damage to the horizontal tail front attachment brackets, accomplish the following:
a. Reinforce the joint between the horizontal tail from attachment brackets, P/N C3-T5-15 and the horizontal tail structure by the installation of a pair of doubler plates on the horizontal tail lower surface skin in accordance with paragraph 6 "PROCEDURE " of DeHavilland Aircraft of Canada, Ltd. Engineering Bulletin, Series "O", No. 33, or an approved equivalent alteration procedure.
b. Replace the existing 5/32 inch diameter dural rivets, P/N AN 456AD5 with 3/16 inch diameter steel bolts, P/N AN 173-6, for the attachment of the front attachment brackets to the horizontal tail, or approved equivalent parts.
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22. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 2 thru 192, except 176, 178, 181 and 190 certificated in all categories, but not altered in accordance with DeHavilland Modification No. 3/729.
Compliance required within the next 50 hours in service after the effective date of this AD.
To prevent the possible loss of the aileron center hinge bearing and to serve as a stop, install bolt, P/N C3-WF-54-3, in the outboard flap center hinge assembly in accordance with the "PROCEDURE" described in DeHavilland Engineering Bulletin, Series "O", No. 30, or with an approved equivalent alteration.
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23. Applies to DHC-3 (U-1A) Airplanes, Serial Number 2 thru 126 except 67, 106, 114 and 120, certificated in all categories, but not altered in accordance with DeHavilland Modification No. 3/711.
Compliance required within the next 50 hours in service after the effective date of this AD.
To prevent buckling or cracking in the nose flap center hinge ribs, reinforce the inboard nose flap center hinge rib in accordance with paragraph 6 "PROCEDURE" in DeHavilland Engineering Bulletin, Series "O", No. 24, or with an approved equivalent alteration.
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24. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 2 thru 270, 272, 275, 276 and 278, certificated in all categories and having steel bushings fitted to flap control rod sub assembly C3CF170-4, Mod. 3/288, but not altered in accordance with DeHavilland Modification No. 3/807.
Compliance required within the next 25 hours in service after the effective date of this AD.
To prevent the possible loss of the flap, replace the flap control rod sub assembly C3CF170-4 with C3CF170-11 in accordance with paragraph 6 "PROCEDURE" in DeHavilland Engineering Bulletin, Series "O", No. 49.
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25. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 2 thru 73 except Serial Numbers 16, 25, 27, 34, 43, 47 thru 51 and 67, certificated in all categories.
Compliance required within the next 100 hours in service after the effective date of this AD, unless already accomplished.
To provide adequate rivet connection of the top outer wing skin to the inner corrugated skin, inspect the top surface of the wing for excessive spacing between rivets, in accordance with paragraph 5 "PROCEDURE" in DeHavilland Engineering Bulletin, Series "O", No. 17 or an approved equivalent inspection.
If excessive rivet spacing exists, install, before next flight, CR-163 4-2 Cherry rivet in accordance with the procedure in DeHavilland Engineering Bulletin, Series "O", No. 17, or with an approved equivalent alteration.
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26. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 2 thru 71 except 16, 25, 27, 34, 43, 47 thru 51 and 54, certificated in all categories, but not altered in accordance with DeHavilland Modification 3/458.
To detect damage to the rudder control system, caused by heavy ground gust conditions on parked aircraft, accomplish the following visual inspection, after the effective date of this AD:
a. Inspect, within the next 25 hours in service, unless already accomplished within the last 25 hours in service.
b. Repeat this inspection at intervals thereafter not to exceed 100 hours in service.
c. Inspect in accordance with paragraph 6 "DATA" in DeHavilland Aircraft, Ltd. Engineering Bulletin, Series Otter, No. 1, or an approved equivalent inspection.
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27. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 2 thru 54, certificated in all categories.
Compliance required within the next 50 hours in service after the effective date of the AD, unless already accomplished.
a. For rudder quadrant hub assemblies, P/N C3-CF-127, install six additional AN 456AD-4-14 rivets in accordance with paragraph 6. "DATA" in DeHavilland Engineering Bulletin, Series Otter, No. 3, or install an approved equivalent alteration.
b. For elevator quadrant hub assemblies, P/N C3-CF-126, replace with P/N C3-CF-126-7, in accordance with paragraph 6. "DATA" in DeHavilland Engineering Bulletin, Series "O", No. 22, or an approved equivalent alteration.
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28. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 1 thru 201, certificated in all categories, incorporating DeHavilland Modification No. 3/731, and P/N C3-CF-450-9 and -11, but not altered in accordance with DeHavilland Modification 3/772.
Compliance required within the next 50 hours in service after the effective date of this AD.
To prevent displacement of the wing flap actuating jack head assembly sintered metal filter, with consequent marginal engagement between the filter internal retainer and seal holder, remove sintered metal filter assembly from flap hydraulic jack, P/N C3-450-9 and -11 in accordance with paragraph 6. "PROCEDURE" in DeHavilland Aircraft of Canada, Ltd., Engineering Bulletin, Series "O", No. 38, or an approved equivalent alteration.
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29. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 1 thru 40, certificated in all categories.
Compliance required within the next 50 hours in service, unless already accomplished.
To provide a more positive retainer for the piston tube of the main landing gear compression strut, P/N C3-U-104, alter the landing gear in accordance with "Modification Procedure" in DeHavilland of Canada, Ltd., Technical News Sheet, Series Otter, No. 23 including amendment No. 1, or an approved equivalent alteration.
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30. Applies to DHC-3 (U-1A) Airplanes, Serial Number 1 thru 15 except 7, certificated in all categories without tail wheel steering, but not altered in accordance with DeHavilland Modification 3/132.
Compliance required within the next 25 hours in service.
To prevent possible loss of tail wheel assembly in flight, install P/Ns C3-UT-40, CW- UT-41, CW-UT-42, in accordance with "Modification Procedure" in DeHavilland Aircraft of Canada, Ltd., Technical News Sheet, Series Otter No. 6, or an approved equivalent alteration.
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31. Applies to all DHC-3 (U-1A) Airplanes equipped with combination wheel-skis, certificated in all categories, but not altered in accordance with DeHavilland Modification 3/874.
Compliance required at the next ski installation or within the next 50 hours in service after the effective date of this AD, whichever occurs first.
To insure adequate lubrication of the main landing ski axle pin, install new axle pin P/N C3U5286-3 and bushing P/N C3U5287-3 in accordance with the "Modification Procedure" in DeHavilland Aircraft of Canada, Ltd., Engineering Bulletin, Series "O", No. 70, Issue 2, and its amendments 1 and 2, or an approved equivalent alteration.
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32. Applies to DHC-3 (U-1A) Airplanes, Serial Numbers 2 thru 37 except 16 and 19, certificated in all categories, but not altered in accordance with DeHavilland Modification No. 3/374.
Compliance required within the next 50 hours in service after the effective date of this AD.
To provide a stronger and more positive attachment of the rear cabin seats to the luggage compartment post, install eyebolts P/N AN 43-17A, in accordance the "Modification Procedure" in DeHavilland of Canada, Ltd., Technical News Sheet, Series Otter, No. 25, or an approved equivalent alteration.
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Equivalent placards, signs, parts, inspection, procedures, instructions, repairs, alterations and modification, as applicable, must be approved by the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region.
Compliance with this Airworthiness Directive must be noted in the log book of the aircraft by referencing the Airworthiness Directive number and the specific item complied with; example: AD 76-08-05(2) if item 22 is being complied with.
Upon request, with substantiating data submitted through an FAA maintenance inspector, the compliance times of this AD may be increased by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region.
This amendment is effective April 29, 1976.
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