Airworthiness Directive · Amendment 39-17505 · Flight controls
Bombardier, Inc. Airplanes
This AD applies to Bombardier, Inc. Model DHC-8-400, -401, and -402 airplanes; certificated in any category; having serial numbers (S/Ns) 4001 through 4334 inclusive, and 4336.
We are superseding airworthiness directive (AD) 2011-13-08 for certain Bombardier, Inc. Model DHC-8-400 series airplanes. AD 2011-13- 08 required a free-play check for excessive free-play of the shaft swaged bearing installed in the tailstock end of each elevator power control unit (PCU), and replacing any PCU on which the bearing exceeds allowable limits with a serviceable PCU. This new AD adds airplanes to the applicability from that of AD 2011-13-08. This AD was prompted by a determination that additional airplanes are affected by the identified unsafe condition. We are issuing this AD to detect and correct excessive free-play of the swaged bearings, which could lead to excessive airframe vibrations and difficulties in pitch control, and consequent loss of controllability of the airplane.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
This paragraph restates the requirements of paragraph (g) of AD 2011-13-08, Amendment 39-16731 (76 FR 37253, June 27, 2011), with revised service information. For airplanes identified in paragraph (c) of this AD, except airplanes having S/N 4305 through 4334 inclusive, and 4336: At the applicable time specified in paragraphs (g)(1) and (g)(2) of this AD, perform a free-play check for any shaft swaged bearing having part number (P/N) MS14103-7 that is installed in the tailstock end of each elevator PCU (three PCUs per elevator surface) having P/Ns 390600-1007 and 390600-1009, in accordance with paragraph 3.B., Part A, of Bombardier Service Bulletin 84-27-52, dated May 25, 2010; or Revision A, dated March 5, 2012. As of the effective date of this AD, only Bombardier Service Bulletin 84-27-52, Revision A, dated March 5, 2012, may be used to accomplish the actions required by this paragraph.
(1) For airplanes that have accumulated 8,000 or more total flight hours as of August 1, 2011 (the effective date of AD 2011-13-08, Amendment 39-16731 (76 FR 37253, June 27, 2011)): Within 2,000 flight hours after August 1, 2011 (the effective date of AD 2011-13-08).
(2) For airplanes that have accumulated less than 8,000 total flight hours as of August 1, 2011 (the effective date of AD 2011-13-08, Amendment 39-16731 (76 FR 37253, June 27, 2011)): Within 6,000 flight hours after August 1, 2011 (the effective date of AD 2011-13-08), or before the accumulation of 10,000 total flight hours, whichever occurs first.
This paragraph restates the requirements of paragraph (h) of AD 2011-13-08, Amendment 39-16731 (76 FR 37253, June 27, 2011), with revised service information. If, during the check required by paragraph (g) of this AD, the bearing free-play is within the limits specified in Bombardier Service Bulletin 84-27-52, dated May 25, 2010, or Revision A, dated March 5, 2012; no further action is required by this AD. As of the effective date of this AD, only Bombardier Service Bulletin 84-27-52, Revision A, dated March 5, 2012, may be used to accomplish the actions required by this paragraph.
This paragraph restates the requirements of paragraph (i) of AD 2011-13-08, Amendment 39-16731 (76 FR 37253, June 27, 2011), with revised service information. If, during the check required by paragraph (g) of this AD, the bearing free-play exceeds the limits specified in Bombardier Service Bulletin 84-27-52, dated May 25, 2010; or Revision A, dated March 5, 2012: Before further flight, replace the elevator PCU with a serviceable one, in accordance with paragraph 3.B., Part B, of Bombardier Service Bulletin 84-27-52, dated May 25, 2010; or Revision A, dated March 5, 2012. As of the effective date of this AD, only Bombardier Service Bulletin 84-27-52, Revision A, dated March 5, 2012, may be used to accomplish the actions required by this paragraph.
For airplanes having S/N 4305 through 4334 inclusive, and 4336: At the applicable time specified in paragraphs (j)(1) and (j)(2) of this AD, perform a free-play check for any shaft swaged bearing having P/N MS14103-7 that is installed in the tailstock end of each elevator PCU (three PCUs per elevator surface), having P/Ns 390600-1007 and 390600-1009, in accordance with paragraph 3.B., Part A, of Bombardier Service Bulletin 84-27-52, Revision A, dated March 5, 2012.
(1) For airplanes that have accumulated 8,000 or more total flight hours as of the effective date of this AD: Within 2,000 flight hours after the effective date of this AD.
(2) For airplanes that have accumulated less than 8,000 total flight hours as of the effective date of this AD: Within 6,000 flight hours after the effective date of this AD, or before the accumulation of 10,000 total flight hours, whichever occurs first.
During the check required by paragraph (j) of this AD, if the bearing free-play is found to exceed the limits specified in Bombardier Service Bulletin 84-27-52, Revision A, dated March 5, 2012: Before further flight, replace the elevator PCU with a serviceable one, in accordance with paragraph 3.B., Part B, of Bombardier Service Bulletin 84-27-52, Revision A, dated March 5, 2012.
