AD 2007-17-17 Airworthiness Directives; Learjet Model 31, 31A, 35, 35A (C-21A), 36, 36A, 55, 55B, and 55C Airplanes, and Model 45 Airplanes

Models named: 45. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to Learjet Model 31, 31A, 35, 35A (C-21A), 36, 36A, 55, 55B, and 55C airplanes, and Model 45 airplanes; certificated in any category; as identified in the service information specified in Table 1 of this AD. Table 1.—Applicable Service Information Learjet airplane model Service Bulletin Revision level Date 31/31A Bombardier Service Bulletin 31-54-2 1 August 21, 2006. 45 Bombardier Service Bulletin 45-54-3 2 August 15, 2003. 35/35A (C-21A) and 36/36A Learjet Service Bulletin 35/36-54-3 Original March 16, 2001. 55/55B/55C Learjet Service Bulletin 55-54-3 Original March 16, 2001.

You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done. Inspecting, Cleaning, and Sealing of Gaps in Engine Firewall (f) Within 12 months after the effective date of this AD, do the actions described in paragraphs (f)(1) and (f)(2) of this AD, in accordance with the applicable service information specified in Table 1 of this AD. (1) For all airplanes: Inspect for unsealed gaps on the pylon side of the engine firewall and clean and seal any unsealed gap. (2) For Learjet Model 45 airplanes only: Inspect the engine pylon trailing edge for unsealed gaps, and clean and seal any unsealed gap. Credit for Actions Done Using Previous Service Information (g) Actions accomplished before the effective date of this AD according to Learjet Service Bulletin 31-54-2, dated March 16, 2001; or Bombardier Service Bulletin 45-54-3, dated March 16, 2001; or Revision 1, dated December 12, 2001; as applicable; are considered acceptable for compliance with the corresponding action specified in this AD. Alternative Methods of Compliance (AMOCs) (h)(1) The Manager, Wichita Aircraft Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19. (2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO. Material Incorporated by Reference (i) You must use the service documents identified in Table 2 of this AD to perform the actions that are required by this AD, unless the AD specifies otherwise. (For Bombardier Service Bulletin 45-54-3, Revision 2, dated August 15, 2003, only the first page of that document contains the correct revision date.) The Director of the Federal Register approved the incorporation by reference of these documents in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Contact Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-2942, for a copy of this service information. You may review copies at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington; or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal-register/cfr/ibr-locations.html. Table 2.—Material Incorporated by Reference Service Bulletin Revision level Date Bombardier Service Bulletin 31-54-2 1 August 21, 2006. Bombardier Service Bulletin 45-54-3 2 August 15, 2003. Learjet Service Bulletin 35/36-54-3 Original March 16, 2001. Learjet Service Bulletin 55-54-3 Original March 16, 2001. Issued in Renton, Washington, on August 14, 2007. Stephen P. Boyd, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. E7-16676 Filed 8-27-07; 8:45 am] BILLING CODE 4910-13-P

This AD results from a report that unsealed gaps (penetration points) of the engine firewall were discovered during production. We are issuing this AD to prevent penetration of flammable liquids or fire through the engine firewall into the engine pylon, which could lead to fire inside the airplane.