AD 2021-23-06 Airworthiness Directives; Various Model 234 and Model CH-47D Helicopters

Models named: 234, Model CH-47D. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to Model 234 and Model CH-47D helicopters, regardless of type certificate holder, certificated in any category. Type certificate holders include, but are not limited to: (1) Columbia Helicopters, Inc., (2) Billings Flying Service, Inc., (3) Tandem Rotor, LLC, and (4) Unical Aviation, Inc.

Comply with this AD within the compliance times specified, unless already done.

(1) Within 3 calendar days after the effective date of this AD, determine the hours time-in-service (TIS) and lift cycles since last overhaul for each LCTA on your helicopter. If lift cycles cannot be determined, count 6 lift cycles for each hour TIS for each LCTA. For purposes of this AD, a lift cycle is defined as any of the following: (i) Takeoff from ground for flight; (ii) Lift of a new external load while in flight; or (iii) Lift of a new internal load while in flight ( e.g., fluid drawn into an internal tank). (2) If the last overhaul of any LCTA was not approved for return to service by a person that meets the requirements of 14 CFR part 43, or, if you are unable to establish hours TIS and lift cycles since last overhaul of an LCTA ( e.g., hours TIS and lift cycles for each LCTA were not tracked), within 10 calendar days after the effective date of this AD, and thereafter at intervals not to exceed 3,000 hours TIS or 18,000 lift cycles, whichever occurs first, overhaul that LCTA. For purposes of any overhaul required by this AD, the overhaul must include: (i) An inspection of each acme screw for wear and cracking; (ii) Lubricating all drive threads and gears; and (iii) A test to ensure proper operation of the extend and retract travel limit switches. (3) If the last overhaul of an LCTA was approved for return to service by a person that meets the requirements of 14 CFR part 43, overhaul the LCTA (to include the overhaul requirements specified in paragraphs (g)(2)(i) through (iii) of this AD) within 500 hours TIS or 3,000 lift cycles since last overhaul, whichever occurs first; or within 90 days after the effective date of this AD, whichever occurs later. Thereafter, overhaul each LCTA at intervals not to exceed 3,000 hours TIS or 18,000 lift cycles, whichever occurs first. (4) As of the effective date of this AD, do not install any LCTA on any helicopter unless it has been approved for return to service by a person that meets the requirements of 14 CFR part 43 after an overhaul that includes the overhaul requirements specified in paragraphs (g)(2)(i) through (iii) of this AD, and that LCTA has not been in service for more than 3,000 hours TIS or 18,000 lift cycles since that overhaul. (5) Within 10 days after completing each LCTA overhaul required by this AD, provide the following information by email to vaughn.n.schmitt@faa.gov and ian.a.hansen@faa.gov; or by mail to Vaughn Schmitt and Ian Hansen, Aircraft Evaluation Group, Safety Standards Division, FAA, 10101 Hillwood Parkway, Fort Worth, TX 76177: (i) Helicopter Owner/Operator name, email, address, and telephone number, (ii) LCTA model, part number and serial number, (iii) Months TIS since last LCTA overhaul, (iv) Operating hours and lift cycles since last LCTA overhaul, (v) Date and location of last LCTA overhaul, (vi) LCTA repairs since last LCTA overhaul, (vii) LCTA condition when removed, (viii) LCTA reports of failures or degraded functions, (ix) LCTA part replacements, (x) Point of contact information for additional information, (xi) Any additional notes or comments, and (xii) Pictures, if available.

This AD was prompted by inadequate maintenance, which resulted in mechanical failure of the longitudinal cyclic trim actuator (LCTA). The FAA is issuing this AD to correct this unsafe condition, which if not addressed, could result in loss of control of the rotor blades and subsequent loss of control of the helicopter or the rotor blades striking the fuselage.

None.