93-25-02 DE HAVILLAND: Amendment 39-8768. Docket 90-NM-129-AD.
Applicability: Model DHC-8-100 and DHC-8-300 series airplanes, having serial numbers 3 through 293, certificated in any category.
Compliance: Required as indicated, unless accomplished previously.
To prevent asymmetrical flap deployment, accomplish the following:
(a) For airplanes having serial numbers 3 through 231, 233, 235, 237, and 243: Within 300 hours time-in-service after the effective date of this AD, accomplish the procedures specified in paragraphs (a)(1), (a)(2), (a)(3), and (a)(4) of this AD:
(1) Locate and inspect the flap primary-drive torque tubes to determine if parts having the part numbers (P/N) and serial numbers (S/N) listed in TABLE 1, below, are installed.
TABLE 1
Torque Tube P/N Series
Torque Tube S/N
734187
125 through 171
734378
129 through 150
734380
127 through 166
734382
211 through 322
734384
153 through 188 and 226 through 235
734386195 through 286
734388
160 through 177
(2) If any torque tube listed in TABLE 1 is installed, prior to further flight, remove the through-bolt from the splined coupling on each end of the torque tube and, using a 10X magnifying glass, perform a detailed visual inspection of the area around the bolt holes for cracks.
(3) If a splined coupling is found to be cracked on a particular torque tube, prior to further flight, accomplish either paragraph (a)(3)(i) or (a)(3)(ii) of this AD:
(i) Replace the splined couplings on that torque tube in accordance with the accomplishment instructions in the appropriate Sundstrand Service Bulletin specified in TABLE 2, below, and re-identify the torque tube as indicated. Marking the service bulletin number on the rod with indelible ink will satisfy this re-identification requirement. Or
(ii) Replace the particular torque tube with a serviceable unit.
NOTE: Some torque tubes have one splined coupling, while others have two.TABLE 2
Torque Tube P/N Series
Sundstrand Alert Service Bulletin No.
Post-Modification
Identification
734187
734187-27-A2, Rev. 1,
dated September 15, 1990
27-A2
734378
734378-27-A3, Rev. 1,
dated January 25, 1991
27-A3
734380
734380-27-A2, Rev. 1,
dated September 15, 1990
27-A2
734382
734382-27-A3, Rev. 1,
dated September 15, 1990
27-A3
734384
734384-27-A2, Rev. 1,
dated September 15, 1990
27-A2
734386
734386-27-A2, Rev. 1,
dated September 15, 1990
27-A2
734388
734388-27-A1, Rev. 1,
dated September 15, 1990
27-A1
(4) Upon reassembly, install the through-bolt, and torque to between 20 and 25 in-lb.
(b) For airplanes having serial numbers 3 through 231, 233, 235, 237, and 243: Within 900 hours time-in-service after the effective date of this AD, replace all splined couplings [which have not been replaced in accordance with paragraph (a)(3)(i) or (a)(3)(ii) of this AD] on torque tubes identified in TABLE 1, above, in accordance with the accomplishment instructions in the appropriate Sundstrand Service Bulletin specified in TABLE 2, above. Re-identify the torque tubes as indicated. Marking the service bulletin number on the rod with indelible ink will satisfy this re-identification requirement.
(c) For airplanes having serial numbers 3 through 293: Within 300 hours time-in- service after the effective date of this AD, and thereafter at intervals not to exceed 300 hours time-in-service, accomplish the following visual inspection procedure of the flap primary-drive torque tube system and the flap secondary-drive flex shaft system:
(1) Extend flaps fully.
(2) Conduct a general visual inspection of the flap primary-drive torque tubes over their entire length for fracture, rubbing, and wear.
(3) Damaged torque tubes, or torque tubes exhibiting wear greater than 0.010 inch in depth or 180 degrees around the circumference, must be replaced with serviceable torque tubes prior to further flight.(4) Conduct a general visual inspection of the flap secondary-drive flex outer sheath casing for permanent deformation (kinks), or evidence of excessive heat of the outer braided sheath, melting of the outer plastic sheath (if installed), or any discoloration of the anodic film on the casing ferrules.
(5) If any of the conditions specified in paragraph (c)(4) of this AD exist, the secondary drive assemblies must be replaced with serviceable units prior to further flight.
(d) For airplanes having serial numbers 3 through 293: Within 600 hours time-in- service after the effective date of this AD, unless previously accomplished within the last 600 hours time-in-service; and thereafter at intervals not to exceed 1,200 hours time-in-service; accomplish the procedures specified in paragraphs (d)(1) and (d)(2) of this AD:
(1) Perform an operational check of the torque sensor in accordance with the following service documents, as appropriate:
(i) For Model DHC-8-100 series airplanes: Maintenance Program Task 2750/11 (refer to DASH 8 Maintenance Program Supplementary Information, PSM 1-8-7, Volume 2, Procedures 27, dated March 30, 1990).
(ii) For Model DHC-8-300 series airplanes: Maintenance Program Task 2750/11 (refer to DASH 8 Maintenance Program Supplementary Information, PSM 1-83-7, Volume 2, Procedures 27, dated December 21, 1988).
(2) Any torque sensor found malfunctioning or jammed must be replaced with a serviceable unit prior to further flight.
(e) For airplanes having serial numbers 3 through 293: Within 2,000 hours time-in- service after the effective date of this AD, or within 9 months after the effective date of this AD, whichever occurs first, modify the wing flap system by installing Modification 8/1473 in accordance with de Havilland Service Bulletin S.B. 8-54-16, Revision 'A', dated October 26, 1990; Modification 8/0803 in accordance with de Havilland Service Bulletin S.B. 8-27-47, Revision 'A', dated July6, 1990; and Modification 8/1649 in accordance with de Havilland Service Bulletin S.B. 8-27-61, dated October 25, 1991. Installation of these modifications constitutes terminating action for the requirements of paragraphs (c) and (d) of this AD.
(f) Installation of Modification 8/1473 in accordance with de Havilland Service Bulletin S.B. 8-54-16, Revision 'A', dated October 26, 1990; Modification 8/0803 in accordance with de Havilland Service Bulletin S.B. 8-27-47, Revision 'A', dated July 6, 1990; and Modification 8/1649 in accordance with de Havilland Service Bulletin S.B. 8-27-61, dated October 25, 1991; constitutes terminating action for the requirements of paragraphs (c) and (d) of this AD.
(g) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, New York Aircraft Certification Office (ACO). Operators shall submit their requests through an appropriate FAA PrincipalMaintenance Inspector, who may add comments and then send it to the Manager, New York ACO.
NOTE: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the New York ACO.
(h) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished.
(i) The replacements and re-identification shall be done in accordance with the following Sundstrand Alert service bulletins, which contain the specified effective pages:
Service Bulletin Referenced and Date
Page Number
Revision Level
Shown on Page
Date
Shown on Page
734187-27-A2,
Revision 1,
September 15, 1990
1-3, 6-7
4-5
1
Original
September 15, 1990
October 20, 1989
734378-27-A3,
Revision 1,
January 25, 1991
1-7
1
January 25, 1991
734380-27-A2,
Revision 1,
September 15, 1990
1-3, 6-7
4-5
1
Original
September 15, 1990
October 20, 1989
734382-27-A3,
Revision 1,
September 15, 1990
1-3, 6-7
4-5
1
Original
September 15, 1990
October 20, 1989
734384-27-A2,
Revision 1,
September 15, 1990
1-3, 6-7
4-5
1
Original
September 15, 1990
October 20, 1989
734386-27-A2,
Revision 1,
September 15, 1990
1-3, 6-7
4-5
1
Original
September 15, 1990
October 20, 1989
734388-27-A1,
Revision 1,
September 15, 1990
1-3, 6-7
4-5
1
Original
September 15, 1990
October 20, 1989
The modifications shall be done in accordance with de Havilland Service Bulletin S.B. 8-54-16, Revision 'A', dated October 26, 1990; de Havilland Service Bulletin S.B. 8-27-47, Revision 'A', dated July 6, 1990; and de Havilland Service Bulletin S.B. 8-27-61, dated October 25, 1991. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies may be obtained from de Havilland, Inc., Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Engine and Propeller Directorate, New York Aircraft Certification Office, 181 South Franklin Avenue, Room 202, Valley Stream, New York; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
(j) This amendment becomes effective on January 19, 1994.