2003-21-03: Low pressure rotor speed (NL) sensor

2003-21-03 Pratt & Whitney Canada: Amendment 39-13338. Docket No. 2003-NE-11-AD. Effective Date (a) This AD becomes effective November 20, 2003. Affected ADs (b) None. Applicability (c) This AD applies to Pratt & Whitney Canada (PWC) models PW118, PW120, PW120A, and PW121 turboprop engines. These engines are installed on, but not limited to, Empresa Brasileira de Aeronautica (EMBRAER) EMB-120RT, 120ER, and 120FC, Bombardier Inc. (formerly Dehavilland of Canada) DHC-8-100 series, and Aerospatiale ATR 42- 200, -300, and -320 airplanes. Unsafe Condition (d) This AD is prompted by a report of an internal oil fire in the engine intercompressor case (ICC). A fire in the ICC could cause the existing tubes to disengage due to melted brazing on the tubes. Once these tubes disengage, the ICC fire then develops into an external fire within the engine nacelle cavity. We are issuing this AD to prevent fire in the engine nacelle cavity, in-flight engine shutdown, and airplane damage. Compliance (e) Compliance with this AD is required at the next engine shop visit, or within 90 days after the effective date of this AD, whichever occurs first, unless already done. Credit for Previous Replacements and Rework (f) Replacements and rework performed before the effective date of this AD, using PWC Service Bulletin (SB) No. 20914, Revision 4, dated December 14, 2001, the original issue, or Revision 1, 2, or 3, satisfy the requirements of paragraphs (g) through (h) of this AD. Low Pressure Rotor Speed (NL) Sensor Port Sealing Tube (g) Replace the low pressure rotor speed (NL) sensor port sealing tube with an improved durability tube, in accordance with paragraphs 3.A.(1) and 3.A.(2), Accomplishment Instructions of PWC SB No. 20914, Revision 4, dated December 14, 2001. Switching Valve-to-Rear Inlet Case Sealing Air Tube Assembly (h) Remove the switching valve-to-rear inlet case sealing air tube assembly, in accordancewith paragraph 3.B.(1), Accomplishment Instructions of PWC SB No. 20914, Revision 4, dated December 14, 2001, and do the following: (1) Either install an improved durability switching valve-to- rear inlet case sealing air tube assembly, in accordance with paragraph 3.B.(9), Accomplishment Instructions of PWC SB No. 20914, Revision 4, dated December 14, 2001; or (2) Rework the switching valve-to-rear inlet case sealing air tube assembly and install tube assembly, in accordance with paragraphs 3.B.(2), 3.B.(4), and 3.B.(9), Accomplishment Instructions of PWC SB No. 20914, Revision 4, dated December 14, 2001. Alternative Methods of Compliance (i) The Manager, Engine Certification Office, has the authority to approve alternative methods of compliance for this AD if requested using the procedures found in 14 CFR 39.19. Material Incorporated by Reference (j) You must use Pratt & Whitney Canada Service Bulletin No. 20914, Revision 4, dated December 14, 2001 to perform the actions required by this AD. The Director of the Federal Register approved the incorporation by reference of this service bulletin in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. You can get a copy from Pratt & Whitney Canada, Technical Publications Department, 1000 Marie Victorin, Longueuil, Quebec J4G 1A1. You can review copies at 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. Related Information (k) Transport Canada airworthiness directive No. CF-2002-10, dated January 28, 2002, also addresses the subject of this AD.