Airworthiness Directive · Amendment 39-17791 · Landing gear
Bombardier, Inc.
This AD applies to all Bombardier, Inc. Model DHC-8-400, -401, and -402 airplanes, certificated in any category.
We are adopting a new airworthiness directive (AD) for all Bombardier, Inc. Model DHC-8-400 series airplanes. This AD was prompted by a report that a batch of main landing gear (MLG) door actuators with a certain part number having certain serial numbers could be assembled with the scraper installed backward. This AD requires repetitive functional checks of the MLG alternate extension system (AES) and eventual replacement of certain MLG door actuators with actuators that have either been reworked or do not have certain serial numbers. We are issuing this AD to prevent incorrectly installed scrapers, which could hinder the operation of the MLG AES, and result in failure of the MLG AES on one side, and consequent unsafe asymmetrical landing configuration.
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 50 flight hours after the effective date of this AD, inspect the MLG door actuators to determine whether part number (P/N) 46830-7 is installed. A review of airplane maintenance records is acceptable in lieu of this inspection if the part number of the MLG door actuator can be conclusively determined from that review.
If, during the inspection to determine the part number of the MLG actuators as required by paragraph (g) of this AD, any MLG door actuator having P/N 46830-7 and a serial number included in paragraph 1.A. “Effectivity,” of Bombardier Service Bulletin 84-32-108, Revision A, dated October 1, 2012, is found; or if the part number is unable to be determined: At the applicable time specified in paragraph (h)(1) or (h)(2) of this AD, do a functional check of the MLG AES, in accordance with Part A of paragraph 3.B. “Procedure,” of the Accomplishment Instructions of Bombardier Service Bulletin 84-32-108, Revision A, dated October 1, 2012. Repeat the functional check thereafter at intervals not to exceed 50 flight cycles until the actions required by paragraph (i) of this AD are done. If the force applied during the functional check exceeds 67 pound-force (lbf), before further flight, replace the affected actuator, in accordance with Part B of paragraph 3.B. “Procedure,” of the Accomplishment Instructions of Bombardier Service Bulletin 84-32-108, Revision A, dated October 1, 2012.
(1) For airplanes with MLG door actuators that have accumulated more than 950 total flight hours as of the effective date of this AD: Within 50 flight hours after the effective date of this AD.
(2) For airplanes with MLG door actuators that have accumulated 950 total flight hours or less as of the effective date of this AD: Within 1,000 flight hours after the effective date of this AD.
At the earlier of the times specified in paragraphs (i)(1) and (i)(2) of this AD: Replace all MLG door actuators having P/N 46830-7 and a serial number included in paragraph 1.A. “Effectivity,” of Bombardier Service Bulletin 84-32-108, Revision A, dated October 1, 2012, with MLG door actuators reworked in accordance with Part B of paragraph 3.B. “Procedure,” of the Accomplishment Instructions of Bombardier Service Bulletin 84-32-108, Revision A, dated October 1, 2012, or with a MLG door actuator having P/N 46830-7 and a serial number that is not included in section 1.A. “Effectivity,” of Bombardier Service Bulletin 84-32-108, Revision A, dated October 1, 2012. Installation of a MLG door actuator having P/N 46830-7 with “Mod Status 32-106” on the identification plate is acceptable for compliance with the requirements of this paragraph.
(1) Prior to the accumulation of 3,000 total flight hours on any MLG door actuator, or within 50 flight hours after the effective date of this AD, whichever occurs later.
(2) Within 12 months or 2,000 flight hours after the effective date of this AD, whichever occurs first.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Appliances and equipment
