Airworthiness Directive · Amendment 39-18592 · Flight controls
Airbus Airplanes
This AD applies to the Airbus airplanes identified in paragraphs (c)(1) through (c)(6) of this AD, certificated in any category, all manufacturer serial numbers.
(1) Airbus Model A300 B2-1A, B2-1C, B2K-3C, B2-203, B4-2C, B4-103, and B4-203 airplanes.
(2) Airbus Model A300 B4-601, B4-603, B4-620, and B4-622 airplanes.
(3) Airbus Model A300 B4-605R and B4-622R airplanes.
(4) Airbus Model A300 F4-605R and F4-622R airplanes.
(5) Airbus Model A300 C4-605R Variant F airplanes.
(6) Airbus Model A310-203, -204, -221, -222, -304, -322, -324, and -325 airplanes.
We are adopting a new airworthiness directive (AD) for all Airbus Model A300 series airplanes; Model A300 B4-600, B4-600R, F4-600R series airplanes, and Model A300 C4-605R Variant F airplanes (collectively called Model A300-600 series airplanes); and Model A310 series airplanes. This AD was prompted by reports of partial loss of no-back brake (NBB) efficiency on the trimmable horizontal stabilizer actuator (THSA). This AD requires an inspection to determine THSA part numbers, serial numbers, and flight cycles on certain THSAs; and repetitive replacement of certain THSAs. We are issuing this AD to prevent loss of THSA NBB efficiency, which, in conjunction with the inability of the power gear to keep the ball screw in its last commanded position, could lead to an uncommanded movement of the horizontal stabilizer, possibly resulting in loss of control of the airplane.
THSAs affected by the requirements of this AD have part numbers (P/Ns) 47142-403, 47142-413, 47142-414, and 47142-423.
Note 1 to paragraph (g) of this AD: FAA AD 2011-15-08, Amendment 39-16755 (76 FR 42029, July 18, 2011), requires installation of three secondary retention plates for the gimbal bearings on the THSA upper primary attachment, which involved a THSA part number change from the -300 series to the -400 series.
Note 2 to paragraph (g) of this AD: The life limits specified in Part 4 of the airworthiness limitations section are still relevant for the affected THSA. This AD addresses a replacement limit for the NBB disks installed on the THSA, not the life limit for the THSA itself.
Before each date and before exceeding the corresponding THSA flight-cycle limits specified in paragraphs (j)(1), (j)(2), and (j)(3) of this AD, do the actions specified in paragraphs (h)(1) and (h)(2) of this AD; and before exceeding the flight-cycle limit corresponding to each date as specified in paragraphs (j)(1), (j)(2), and (j)(3) of this AD, do the actions specified in paragraph (i) of this AD.
(1) Do an inspection of the THSA to determine the part number and serial number. A review of airplane maintenance records is acceptable in lieu of this inspection if the part number and serial number of the THSA can be conclusively determined from that review.
(2) Do an inspection of the airplane maintenance records to determine the flight cycles accumulated on each affected THSA since first installation on an airplane, or since last NBB replacement, whichever is later. If no maintenance records conclusively identifying the last NBB disk replacement are available, the flight cycles accumulated since first installation of the THSA on an airplane apply.
By each date specified in paragraphs (j)(1), (j)(2), and (j)(3) of this AD, for those affected THSAs having reached or exceeded the corresponding number of flight cycles specified in paragraphs (j)(1), (j)(2), and (j)(3) of this AD, replace the THSA with a serviceable unit, in accordance with the Accomplishment Instructions of Airbus Service Bulletin A300-27-6070, dated February 17, 2015; or Airbus Service Bulletin A310-27-2106, dated February 17, 2015, as applicable.
Paragraphs (j)(1), (j)(2), and (j)(3) of this AD specify compliance dates and THSA flight-cycle limits for accomplishing the actions required by paragraphs (h) and (i) of this AD.
(1) As of 30 days after the effective date of this AD: The affected THSA flight-cycle limit is 30,000 flight cycles since first installation of the THSA on an airplane, or since last NBB replacement, whichever is later.
(2) As of February 1, 2017: The affected THSA flight-cycle limit is 20,000 flight cycles since first installation of the THSA on an airplane, or since last NBB replacement, whichever is later.
(3) As of February 1, 2019: The affected THSA flight-cycle limit is 14,600 flight cycles since first installation of the THSA on an airplane, or since last NBB replacement, whichever is later.
For the purpose of this AD, a serviceable THSA is a unit identified in paragraph (k)(1) or (k)(2) of this AD.
(1) A THSA identified in paragraph (g) of this AD that, as of each date specified in paragraphs (j)(1), (j)(2), and (j)(3) of this AD, has not exceeded the flight-cycle limits specified in paragraphs (j)(1), (j)(2), and (j)(3) of this AD since first installation of the THSA on an airplane, or since the last NBB disk replacement, whichever is later.
(2) A THSA with a different part number (e.g., a THSA that is not identified in paragraph (g) of this AD) that is not affected by the requirements of this AD.
As of each date and before exceeding the flight-cycle limit corresponding to each date specified in paragraphs (j)(1), (j)(2), and (j)(3) of this AD: Replace each affected THSA with a serviceable unit, in accordance with the Accomplishment Instructions of Airbus Service Bulletin A300-27-6070, dated February 17, 2015; or Airbus Service Bulletin A310-27-2106, dated February 17, 2015.
Before each date specified in paragraphs (j)(1), (j)(2), and (j)(3) of this AD, an operator may install an affected THSA on an airplane, provided that the unit has not exceeded the corresponding number of flight cycles specified in paragraphs (j)(1), (j)(2), and (j)(3) of this AD, since first installation on an airplane, or since last NBB replacement, whichever is later.
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.
