AD 2011-17-12

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 5,000 flight hours or 24 months after the effective date of this AD, whichever occurs first, inspect for the part number and serial number of each transcowl assembly, and, as applicable, the repair status of each transcowl assembly. A review of airplane maintenance records is acceptable in lieu of this inspection if the part number and serial number of each transcowl assembly, and, as applicable, the repair status of each transcowl assembly can be conclusively determined from that review.

(1) If all transcowl assemblies installed on any airplane meet one of the conditions listed in paragraph (g)(1)(i), (g)(1)(ii), or (g)(1)(iii) of this AD, no further action is required by this AD, except paragraph (k) of this AD must be complied with.

(i) Having part number (P/N) KCN624-2003-3, -4, -5, -6, -7, or -8, as listed in Bombardier Service Bulletin 670SH-78-029, Revision C, dated November 10, 2010.

(ii) Having P/Ns CN624-2001-XXX or KCN624-2001-X (XXX and X mean various dash numbers), with serial number (S/N) SB0965 or higher.

(iii) Having P/Ns CN624-2001-XXX or KCN624-2001-X (XXX and X mean various dash numbers), and repaired in accordance with one of the Bombardier repair engineering orders (REOs) listed in paragraph 1.D. of Bombardier Service Bulletin 670BA-78-008, Revision B, dated December 22, 2010; or paragraph 1.A. of Bombardier Service Bulletin 670SH-78-029, Revision C, dated November 10, 2010.

(2) If one or more of the transcowl assemblies have P/N CN624-2001-XXX or KCN624-2001-X (XXX and X mean various dash numbers), with S/N SB0964 or lower, and have not been repaired in accordance with one of the Bombardier REOs listed in paragraph 1.D. of Bombardier Service Bulletin 670BA-78-008, Revision B, dated December 22, 2010; or paragraph 1.A. of Bombardier Service Bulletin 670SH-78-029, Revision C, dated November 10, 2010; do the actions specified in paragraph (i) of this AD.

(h) As of the effective date of this AD, if any high-energy stop occurs and the thrust reversers are deployed above 68% N1, or if a rejected take-off (RTO) occurs and the thrust reversers are deployed above 68% N1: Perform a detailed inspection for cracks of each transcowl assembly (left, right, upper, and lower) before further flight, by doing the actions specified in paragraphs (h)(1), (h)(2), and (h)(3) of this AD. Doing the requirements of paragraph (i) of this AD terminates the requirements of paragraph (h) of this AD.

(1) Open the cowling on the left and right engines.

(2) Do a detailed inspection for cracks of the joint extrusion of the upper and lower transcowl assembly on the left and right engines at the location of the joint piece. If no cracks are found, close the cowlings on the left and right engines.

(3) If any crack is found on one or more transcowl assemblies during the inspection required by paragraph (h)(2) of this AD, before further flight, repair and reinforce the cracked part(s) in accordance with paragraph (i)(1) of this AD.

Note 1: Procedure—Part 3 of Task 05-51-27-210-801 of Chapter 05, Part 2, Volume 1, of the Bombardier CRJ Series Regional Jet Aircraft Maintenance Manual (AMM), CSP B-001, Revision 34, dated November 20, 2010, provides guidance for opening and closing the cowling on the left and right engines.

(i) For transcowl assemblies identified in paragraph (g)(2) of this AD: Except as required by paragraph (h) of this AD, within 5,000 flight hours or 24 months after the effective date of this AD, whichever comes first, do a detailed inspection for cracking on each transcowl assembly, in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 670BA-78-008, Revision B, dated December 22, 2010; or Bombardier Service Bulletin 670SH-78-029, Revision C, dated November 10, 2010. Accomplishment of the actions specified in paragraph (i)(1) or (i)(2) of this AD for all transcowl assemblies identified in paragraph (g)(2) of this AD terminates the requirements of paragraph (h) of this AD.

(1) If any cracking of the joint extrusion is found, before further flight, repair and reinforce the joint extrusion on each transcowl assembly, in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 670BA-78-008, Revision B, dated December 22, 2010; or Bombardier Service Bulletin 670SH-78-029, Revision C, dated November 10, 2010.

(2) If no cracking is found, before further flight, reinforce the joint extrusion on each transcowl assembly, in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 670BA-78-008, Revision B, dated December 22, 2010; or Bombardier Service Bulletin 670SH-78-029, Revision C, dated November 10, 2010.

Inspections, repairs, and reinforcement of the joint extrusion on each transcowl is also acceptable for compliance with the corresponding requirements of paragraph (i) of this AD if done before the effective date of this AD in accordance with the service information listed in table 1 of this AD.

As of the effective date of this AD, no replacement or spare transcowl assembly having P/N CN624-2001-XXX or KCN624-2001-X (XXX and X mean various dash numbers), with S/N SB0964 or lower, may be installed on any airplane, except for a transcowl assembly on which any repair listed in paragraph 1.D. of Bombardier Service Bulletin 670BA-78-008, Revision B, dated December 22, 2010, or paragraph 1.A. of Bombardier Service Bulletin 670SH-78-029, Revision C, dated November 10, 2010, has been done; and except for a transcowl that has been inspected as specified in paragraph (i) of this AD and all applicable actions specified in paragraph (i)(1) or (i)(2) of this AD, as applicable, have been done.

Note 2: This AD differs from the MCAI and/or service information as follows: No differences.