Airworthiness Directive · Amendment 39-14847 · Fokker Model F27 Mark 500 Airplanes
Fokker Model F27 Mark 500 Airplanes
This AD applies to all Fokker Model F27 Mark 500 airplanes, certificated in any category.
The FAA is adopting a new airworthiness directive (AD) for all Fokker Model F27 Mark 500 airplanes. This AD requires an inspection to determine whether certain main landing gear (MLG) drag stay units (DSUs) are installed. This AD also requires an ultrasonic inspection to determine if certain tubes are installed in the affected DSUs of the MLG, and related investigative/corrective actions if necessary. This AD results from a report that, due to fatigue cracking from an improperly machined radius of the inner tube, a drag stay broke, and, consequently, led to the collapse of the MLG during landing. We are issuing this AD to prevent such fatigue cracking, which could result in reduced structural integrity or collapse of the MLG.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
Within 60 days after the effective date of this AD: Inspect the MLG drag stay units (DSUs) to determine whether Dowty Aerospace is the manufacturer and, before further flight, inspect Dowty Aerospace MLG DSUs to determine whether part number (P/N) 200261001, 200261002, 200485001, 200485002, 200684001, or 200684002 is installed. A review of the airplane maintenance records is acceptable in lieu of these inspections if the manufacturer and the part number of the MLG DSU can be conclusively determined from that review. For airplanes equipped with MLG DSUs other than Dowty Aerospace MLG DSUs, and for airplanes equipped with Dowty Aerospace MLG DSUs having part numbers other than P/N 200261001, 200261002, 200485001, 200485002, 200684001, and 200684002, no further action is required by this AD, except as specified in paragraph (k) of this AD.
(g) For airplanes equipped with DSUs having P/N 200261001, 200485001, or 200684001: Within 60 days after the effective date of this AD, perform an ultrasonic inspection to determine if a tube having P/N 200485300 with a straight bore, or a tube having P/N 200259300 with a change in section (stepped bore), is installed on the DSUs of the MLG, in accordance with the Accomplishment Instructions of Fokker Service Bulletin F27/32-171, dated December 16, 2004.
Note 1: Fokker Service Bulletin F27/32-171, dated December 16, 2004, refers to Dowty Aerospace Landing Gear Service Bulletin 32-82W, Revision 2, including Appendix A, dated July 29, 1994, and including Appendix B, Revision 1, dated November 10, 1993; and Dowty Aerospace Landing Gear Service Bulletin 32-169B, Revision 2, including Appendix A, dated July 29, 1994, and including Appendix B, Revision 1, dated November 10, 1993; as applicable, as appropriate sources of service information for inspecting MLG DSUs.
(h) If any tube having P/N 200485300 with a straight bore is found installed during the inspection required by paragraph (g) of this AD: Before further flight, re-identify the DSU with P/N 200261004, 200485004, or 200684004, in accordance with the Accomplishment Instructions of Dowty Aerospace Landing Gear Service Bulletin 32-82W, Revision 2, including Appendix A, dated July 29, 1994, and including Appendix B, Revision 1, dated November 10, 1993; or Dowty Aerospace Landing Gear Service Bulletin 32-169B, Revision 2, including Appendix A, dated July 29, 1994, and including Appendix B, Revision 1, dated November 10, 1993; as applicable. After re-identifying the DSU, no further action is required by this AD for that DSU; however airplanes are still subject to the requirements specified in paragraph (k) of this AD.
(i) If any tube having P/N 200259300 with a change in section (stepped bore) is found installed during the inspection required by paragraph (g) of this AD: Before further flight, re-identify the DSU in accordance with paragraphs 2.A.(4)(a) and 2.A.(4)(b) of the Accomplishment Instructions of Dowty Aerospace Landing Gear Service Bulletin 32-82W, Revision 2, including Appendix A, dated July 29, 1994, and including Appendix B, Revision 1, dated November 10, 1993; or Dowty Aerospace Landing Gear Service Bulletin 32-169B, Revision 2, including Appendix A, dated July 29, 1994, and including Appendix B, Revision 1, dated November 10, 1993; as applicable. Following accomplishment of the re-identification, before further flight, do the inspection specified in paragraph (j) of this AD.
For airplanes equipped with re-identified DSUs having P/N 200261002, 200485002, 200684002, 200261003, 200485003, or 200684003: Within 60 days after the effective date of this AD, perform an ultrasonic inspection to detect cracking in the re-identified DSUs, in accordance with the Accomplishment Instructions of Dowty Aerospace Landing Gear Service Bulletin 32-82W, Revision 2, including Appendix A, dated July 29, 1994, and including Appendix B, Revision 1, dated November 10, 1993; or Dowty Aerospace Landing Gear Service Bulletin 32-169B, Revision 2, including Appendix A, dated July 29, 1994, and including Appendix B, Revision 1, dated November 10, 1993; as applicable.
(1) For airplanes equipped with any DSU re-identified as P/N 200684003, 200261003, or 200485003: If no crack is detected, no further action is required by this AD for that DSU; however airplanes are still subject to the requirements specified in paragraph (k) of this AD.
(2) For airplanes equipped with any DSU re-identified as P/N 200684002, 200261002, or 200485002: If no crack is detected, do the actions specified in paragraphs (j)(2)(i) and (j)(2)(ii) of this AD.
(i) Repeat the ultrasonic inspection required by paragraph (j) of this AD thereafter at intervals not to exceed 1,500 flight cycles until the actions specified in paragraph (j)(2)(ii) of this AD are done.
(ii) At the next MLG overhaul but no later than 12,000 flight cycles after the effective date of this AD, rework and re-identify the DSU as P/N 200261003, 200485003, or 200684003, as applicable, in accordance with the applicable service bulletin.
(3) If any crack is detected and the crack signal indication of any DSU tube is greater than or equal to 80 percent, before further flight, replace the DSU with a re-identified DSU having P/N 200261004, 200485004, 200684004, 200261003, 200485003, or 200684003, in accordance with the applicable service bulletin.
(4) If any crack is detected and the crack signal indication of any DSU tube is greater than zero percent but less than 80 percent, do the actions specified in paragraphs (j)(4)(i) and (j)(4)(ii) of this AD.
(i) Repeat the ultrasonic inspection required by paragraph (j) of this AD thereafter at intervals not to exceed 1,500 flight cycles until the actions specified in paragraph (j)(4)(ii) of this AD are done.
(ii) At the next MLG overhaul but no later than 12,000 flight cycles after the effective date of this AD, replace the DSU with a DSU having P/N 200261004, 200485004, 200684004, 200261003, 200485003, or 200684003, in accordance with the applicable service bulletin.
As of the effective date of this AD, no person may install a MLG DSU, P/N 200261001, 200261002, 200485001, 200485002, 200684001, or 200684002, on any airplane, except as specified in paragraph (i) of this AD.
