AD 99-14-06 Airworthiness Directives; MT-Propeller Entwicklung GMBH Models MTV-9-B-C and MTV-3-B-C Propellers

Makes named: mt-propeller. Models named: MTV-9-B-C, MTV-3-B-C. Read the applicability below — it usually turns on serial or part numbers too.

MT-Propeller Entwicklung GMBH Model MTV-9-B-C propellers with serial numbers (S/Ns) starting with 98 or less, equipped with CL250-27 or CL260-27 blades with S/Ns starting with letter ``A'' through ``P'', equipped with Torx head blade root lag screws, P/N A-549-85 (3mm thread pitch), or P/N A-550-85 (4mm thread pitch); and Model MTV-3-B-C propellers with S/Ns starting with 98 or less, equipped with L250-21 blades with S/Ns starting with letter ``A'' through ``P'', equipped with Torx head blade root lag screws, P/N A-549-85 (3mm thread pitch), or A-550-85 (4mm thread pitch). These propellers are installed on but not limited to Sukhoi SU-26, SU-29, SU-31; Yakovlev YAK-52, YAK-54, YAK-55, and Technoavia SM-92 airplanes. Note 1: This airworthiness directive (AD) applies to each propeller identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For propellers that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (d) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Required as indicated, unless accomplished previously. To prevent blade root lag screw breakage, which could result in propeller blade separation and loss of control of the airplane, accomplish the following: (a) For propellers with Torx head blade root lag screws, P/N A- 549-85 (3mm thread pitch), perform initial and repetitive inspections of Torx head blade root lag screws for torque values and breakage, and, if necessary, replace with new lag screws, in accordance with MT-Propeller Entwicklung GMBH Service Bulletin (SB) No. 17-A, dated March 5,1999, as follows: (1) Initially inspect within 50 hours time-in-service (TIS), or within 2 months after the effective date of this AD, whichever occurs first. (2) Thereafter, inspect at intervals not to exceed 100 hours TIS, or within 12 months, whichever occurs first. (3) Prior to further flight, if any Torx head blade root lag screws are found broken or with torque less than 64 foot-pounds, replace all Torx head blade root lag screws with new lag screws. (b) For propellers with Torx head blade root lag screws, P/N A- 550-85 (4mm thread pitch), perform a one-time inspection of Torx head blade root lag screws for torque values and breakage, and, if necessary, replace with lag screws, in accordance with MT-Propeller Entwicklung GMBH SB No. 17-A, dated March 5,1999, as follows: (1) Inspect within 50 hours TIS, or within 2 months after the effective date of this AD, whichever occurs first. (2) Prior to further flight, if any Torx head blade root lag screws are found broken or with torque less than 64 foot-pounds, replace all Torx head blade root lag screws with improved, hexagonal head blade root lag screws, P/N A-983-85. (c) For propellers with Torx head blade root lag screws, P/N A- 550-85 (4mm thread pitch), within 100 hours TIS, or within 12 months after the effective date of this AD, replace all Torx head blade root lag screws, P/N A-550-85, with improved, hexagonal head blade root lag screws, P/N A-983-85, in accordance with MT-Propeller Entwicklung GMBH SB No. 17-A, dated March 5,1999. (d) 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, Boston Aircraft Certification Office. Operators shall submit their requests through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Boston Aircraft Certification Office. Note 2: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Boston Aircraft Certification Office. (e) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the inspection requirements of this AD can be accomplished. (f) The actions required by this AD shall be performed in accordance with the following MT-Propeller Entwicklung GMBH SB: ------------------------------------------------------------------------ Document No. Pages Date ------------------------------------------------------------------------ 17-A.................................. 1-3 March 5, 1999 Total pages: 3. ------------------------------------------------------------------------ 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 MT-Propeller Entwicklung GMBH, Airport Straubing-Wallmuhle, D-94348 Atting, Germany; telephone (0 94 29) 84 33, fax (0 94 29) 84 32, Internet: `` [email protected] ''. Copies may be inspected at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA; or at the Office of the Federal Register, 800 North Capitol Street, NW, suite 700, Washington, DC. (g) This amendment becomes effective on July 23, 1999. [[Page 36779]] Issued in Burlington, Massachusetts, on June 23, 1999. Jay J. Pardee, Manager, Engine and Propeller Directorate, Aircraft Certification Service. [FR Doc. 99-16745 Filed 7-7-99; 8:45 am] BILLING CODE 4910-13-U