92-24-02 DE HAVILLAND: Amendment 39-8407. Docket No. 91-CE-93-AD.
Applicability: Model DHC-2 Beaver MK-I, MK-II, and MK-III airplanes (all serial numbers), certificated in any category.
Compliance: Required as indicated, unless already accomplished.
To prevent horizontal stabilizer front center spar failure, which could lead to loss of control of the airplane, accomplish the following:
NOTE 1: The compliance times specified in this AD take precedence over those referenced in the service information.
(a) Within the next 4 calendar months after the effective date of this AD, accomplish the following:
(1) Dye penetrant inspect the horizontal stabilizer front center spar for cracks in accordance with paragraphs 1, 2, and 3 of Part A. of the ACCOMPLISHMENT INSTRUCTIONS section of de Havilland Service Bulletin (SB) 2/47, Revision C, dated September 4, 1992.
(i) If no cracks are found, accomplish the requirements of paragraph (a)(2) of this AD oraccomplish the requirements of paragraph 5 of Part A. of the ACCOMPLISHMENT INSTRUCTIONS section of de Havilland SB 2/47, Revision C, dated September 4, 1992, whichever is applicable.
(ii) If cracks are found on airplanes not having a gusset plate installed on the rear face of the horizontal stabilizer front center spar (Pre-Modification 2/758), prior to further flight, replace the horizontal stabilizer front center spar in accordance with Part B. of the ACCOMPLISHMENT INSTRUCTIONS section of de Havilland SB 2/47, Revision C, dated September 4, 1992.
(iii) If cracks are found on airplanes that have a gusset plate installed on the rear face of the horizontal stabilizer front center spar (Post-Modification 2/758), within the next 8 calendar months, replace the horizontal stabilizer front center spar in accordance with Part B. of the ACCOMPLISHMENT INSTRUCTIONS section of de Havilland SB 2/47, Revision C, dated September 4, 1992.
(2) For airplanes that have lighteningholes in the horizontal stabilizer front center spar (Pre-Modification 2/466) and that did not have the horizontal stabilizer front center spar replaced as required by either paragraph (a)(1)(ii) or (a)(1)(iii) of this AD, visually inspect the front spar web for cracks in accordance with paragraph 4 of Part A. of the ACCOMPLISHMENT INSTRUCTIONS section of de Havilland SB 2/47, Revision C, dated September 4, 1992.
(i) If no cracks are found, accomplish the requirements of paragraph 5 of Part A. of the ACCOMPLISHMENT INSTRUCTIONS section of de Havilland SB 2/47, Revision C, dated September 4, 1992.
(ii) If any cracks are found, prior to further flight, replace the horizontal stabilizer front center spar in accordance with Part B. of the ACCOMPLISHMENT INSTRUCTIONS section of de Havilland SB 2/47, Revision C, dated September 4, 1992.
NOTE 2: De Havilland SB 2/47, Revision C, dated September 4, 1992, references both the horizontal stabilizer front center spar and the tailplane front center spar. These are one and the same. For the purposes of this AD, all reference is to the horizontal stabilizer front center spar.
(b) If any previously stop-drilled cracks are found per the inspections specified in paragraphs (a)(1) and (a)(2) of this AD, within the following time frames, replace the horizontal stabilizer front center spar in accordance with Part B. of the ACCOMPLISHMENT INSTRUCTIONS section of de Havilland SB 2/47, Revision C, dated September 4, 1992, unless already accomplished in accordance with either paragraph (a)(1)(ii), (a)(1)(iii), or (a)(2)(ii) of this AD:
(1) Within the next 12 calendar months if the stop-drilled cracks have not progressed past the stop.
(2) Within the next 8 calendar months if the stop-drilled cracks have progressed past the stop and the airplane has a gusset plate installed on the rear face of the horizontal stabilizer front center spar (Post-Modification 2/758).
(3) Prior to further flight if thestop-drilled cracks have progressed past the stop and the airplane does not have a gusset plate installed on the rear face of the horizontal stabilizer front center spar (Pre-Modification 2/758).
(c) Within the next 24 calendar months after the effective date of this AD, accomplish the following:
(1) For airplanes having serial numbers (S/N) 1 through 100, install longer pick-up brackets (Modification 2/436) in accordance with the instructions in de Havilland Technical News Sheet B55, dated August 1, 1952, unless already incorporated.
NOTE 3: Modification 2/436 was incorporated at manufacture on airplanes beginning with S/N 101. Other airplanes may have incorporated this modification in the field.
(2) For airplanes having S/N 1 through 317, install a gusset plate on the rear face at each of the pick-up brackets (Modification 2/758) in accordance with the instructions in de Havilland Technical News Sheet B55, dated August 1, 1952, unless already incorporated.NOTE 4: Modification 2/758 was incorporated at manufacture on airplanes beginning with S/N 318. Other airplanes may have incorporated this modification in the field.
NOTE 5: Modification 2/466 - installation of tailplane front spar without lightening holes - is referenced in de Havilland SB 2/47, Revision C, dated September 4, 1992. Accomplishment of this AD incorporates this modification.
(d) Within the next 24 calendar months after the effective date of this AD or within 24 calendar months after accomplishing the requirements of paragraph (c) of this AD, whichever occurs later, and thereafter at intervals not to exceed 24 calendar months, visually inspect the front face of the horizontal stabilizer front center spar for cracks. If any cracks are found, prior to further flight, obtain a repair scheme from the manufacturer through the New York Aircraft Certification Office at the address specified in paragraph (f) of this AD, and accomplish the repair in accordance with the repair scheme obtained.
(e) 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.
(f) An alternative method of compliance or adjustment of the compliance times that provides an equivalent level of safety may be approved by the Manager, New York Aircraft Certification Office, 181 South Franklin Avenue, Room 202, Valley Stream, New York 11581. The request shall be forwarded through an FAA Maintenance Inspector, who may add comments and then send it to the Manager, New York Aircraft Certification Office.
NOTE 6: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the New York Aircraft Certification Office.
(g) The inspections and modifications required by this AD shall be done in accordance with de Havilland Service Bulletin 2/47, Revision C, dated September 4, 1992; and deHavilland Technical News Sheet B55, dated August 1, 1952. 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., Downsview, Ontario, Canada, M2K 1Y5. Copies may be inspected at the FAA, Central Region, Office of the Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri, or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
(h) This amendment becomes effective on December 15, 1992.