Airworthiness Directive · Amendment 39-18625 · Flight controls
Airbus Airplanes
Superseded. A later AD replaced this one: AD 2022-07-08. Comply with the one in force.
This AD applies to Airbus airplanes, certificated in any category, identified in paragraphs (c)(1), (c)(2), (c)(3), and (c)(4) of this AD, all manufacturer serial numbers.
(1) Model A318-111, -112, -121, and -122 airplanes.
(2) Model A319-111, -112, -113, -114, -115, -131, -132, and -133 airplanes.
(3) Model A320-211, -212, -214, -231, -232, and -233 airplanes.
(4) Model A321-111, -112, -131, -211, -212, -213, -231, and -232 airplanes.
We are adopting a new airworthiness directive (AD) for all Airbus Model A318 and A319 series airplanes, Model A320-211, -212, - 214, -231, -232, and -233 airplanes, and Model A321 series airplanes. This AD was prompted by a report of a partial loss of the no-back brake (NBB) efficiency during endurance qualification tests on the trimmable horizontal stabilizer actuator (THSA). This AD requires inspecting certain THSAs to determine the number of total flight cycles the THSA has accumulated, and replacing the THSA if necessary. We are issuing this AD to prevent premature wear of the carbon friction disks on the NBB of the THSA, which could lead to reduced braking efficiency in certain load conditions, and, in conjunction with the inability of the power gear train to keep the ball screw in its last commanded position, could result in uncommanded movements of the trimmable horizontal stabilizer and loss of control of the airplane.
No later than each date specified in paragraphs (g)(1) through (g)(5) of this AD: Inspect the THSA to determine if it has a part number (P/N) 47145-(XXX), and, if any THSA P/N 47145-(XXX) is found, determine the total number of flight cycles accumulated since the THSA's first installation on an airplane, or since the most recent NBB replacement, whichever is later. A review of airplane delivery or maintenance records is acceptable in lieu of this inspection if the part number of the THSA can be conclusively determined from that review. In case maintenance records concerning the most recent NBB disk replacement are unavailable or incomplete, the total flight cycles accumulated since first installation of the THSA on an airplane apply.
(1) As of the effective date of this AD: The THSA flight-cycle limit (since first installation on an airplane, or since the most recent NBB replacement, whichever is later) is 40,000 total flight cycles.
(2) As of December 31, 2016: The THSA flight-cycle limit (since first installation on an airplane, or since the most recent NBB replacement, whichever is later) is 36,000 total flight cycles.
(3) As of December 31, 2017: The THSA flight-cycle limit (since first installation on an airplane, or since the most recent NBB replacement, whichever is later) is 33,600 total flight cycles.
(4) As of December 31, 2018: The THSA flight-cycle limit (since first installation on an airplane, or since the most recent NBB replacement, whichever is later) is 31,600 total flight cycles.
(5) As of December 31, 2019: The THSA flight-cycle limit (since first installation on an airplane, or since the most recent NBB replacement, whichever is later) is 30,000 total flight cycles.
For airplanes with any THSA P/N 47145-(XXX): Do the replacements required by paragraphs (h)(1) and (h)(2) of this AD.
(1) No later than each date specified in paragraphs (g)(1) through (g)(5) of this AD, replace all THSA that have reached or exceeded on each date the corresponding number of flight cycles specified in paragraphs (g)(1) through (g)(5) of this AD. Do the replacement in accordance with the Accomplishment Instructions of Airbus Service Bulletin A320-27-1242, Revision 01, dated February 4, 2016. Affected THSAs must be replaced with serviceable THSAs.
(2) As of each date specified in paragraphs (g)(1) through (g)(5) of this AD, and before exceeding the flight cycle limit corresponding to each date, as applicable: Replace each THSA with a serviceable THSA, in accordance with the Accomplishment Instructions of Airbus Service Bulletin A320-27-1242, Revision 01, dated February 4, 2016.
For the purposes of this AD: A serviceable THSA is a THSA that has not exceeded the applicable flight-cycle limits, as specified paragraphs (g)(1) through (g)(5) of this AD, since first installation of the THSA on an airplane or since last NBB replacement, whichever is later.
Note 1 to paragraph (i) of this AD: Guidance for NBB disc replacement can be found in UTC Aerospace Systems Service Bulletin 47145-27-17, Revision 1, dated July 21, 2015.
As of each date specified in paragraphs (g)(1) through (g)(5) of this AD, as applicable, only installation of a serviceable THSA P/N 47145-(XXX) is allowed on an airplane.
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.
