Airworthiness Directive · Amendment 39-15778 · Flight controls
Aircraft Industries a.s. (Type Certificate G60EU previously held by LETECKÉ ZÁVODY a.s. and LET Aeronautical Works) Model L 23 Super Blanik Sailplane
This AD applies to Model L 23 Super Blanik sailplanes, all serial numbers, certificated in any category.
We are adopting a new airworthiness directive (AD) for the products listed above. This AD results from mandatory continuing airworthiness information (MCAI) issued by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:
Unless already done, do the following actions:
(1) Within the next 3 months after January 28, 2009 (the effective date of this AD) and repetitively thereafter at intervals not to exceed 12 months, visually inspect the control bridge in areas of juncture with the two control sticks for cracks. Do the inspection following paragraph A of LET Aircraft Industries, a.s. Mandatory Bulletin MB No. L23/050a, Revision No. 2, dated September 12, 2007, except use a 10X magnifier and do a dye penetrant inspection following the procedures in chapter 5, section 5, of FAA Advisory Circular AC 43.13-1B CHG 1, dated September 27, 2001.
(2) If cracks are found in the control bridge bedding during any inspection required in paragraph (f)(1) of this AD, before further flight, replace the defective control bridge bedding, Dwg. No. A740 371N, in the control bridge assembly, Dwg. No. A740 370N, following LET Aircraft Industries, a.s. Mandatory Bulletin MB No. L23/050a, Revision No. 2, dated September 12, 2007; and Appendix No. 1, “Replacement of Bearings 608 CSN 024630 at Control Bridge Dwg. No. A740 370N in a Bedding Dwg. No. A740 371N,” to LET Aircraft Industries, a.s. Mandatory Bulletin MB No. L23/050a, Revision No. 2, dated September 12, 2007.
(3) Doing the replacement required in paragraph (f)(2) of this AD terminates the 12-month repetitive inspection required in paragraph (f)(1) of this AD. After the replacement required in paragraph (f)(2) of this AD, perform subsequent inspections on the new control bridge assembly according to LET Aircraft Industries, a.s. Documentation Bulletin No.: L23/020 d, dated August 6, 2007.
Note: This AD differs from the MCAI and/or service information as follows: (1) The service information requires a visual inspection with a 6X magnifier. We are requiring a dye penetrant inspection and a 10X magnifier to detect cracks that could go undetected using only a 6X magnifier. (2) The MCAI requires updating the maintenance manuals to add repetitive inspections of the control bridge. Since the maintenance manual is only one way of establishing a maintenance program, the only way we can mandate these repetitive inspections is through an AD action. We have made these repetitive inspections part of this AD.
