Airworthiness Directive · Amendment 39-21749 · Rotorcraft flight control
Bell Textron Canada Limited (Type Certificate Previously Held by Bell Helicopter Textron Canada Limited) Helicopters
This AD applies to Bell Textron Canada Limited (type certificate previously held by Bell Helicopter Textron Canada Limited) Model 429 helicopters, certificated in any category, serial numbers 57001 through 57210 inclusive, 57212 through 57344 inclusive, 57346 through 57371 inclusive, 57374 through 57377 inclusive, and 57380.
The FAA is adopting a new airworthiness directive (AD) for certain Bell Textron Canada Limited (type certificate previously held by Bell Helicopter Textron Canada Limited) Model 429 helicopters. This AD was prompted by reports of incorrectly staked spherical bearings in the directional control bellcrank assembly. This AD requires a one-time inspection of the lower surface of the spherical bearing in the directional control bellcrank assembly to determine if it is properly staked and, depending on the findings, applicable corrective actions. For certain helicopters, this AD also requires repetitive inspections and, depending on the findings, applicable corrective actions. This AD also provides a terminating action for the repetitive inspections. The FAA is issuing this AD to address the unsafe condition on these products.
Within 25 hours time-in-service (TIS) or 90 days, whichever occurs first after the effective date of this AD: Inspect the lower surface of the spherical bearing on the directional control bellcrank assembly to determine if it is properly staked, in accordance with the Accomplishment Instructions, Part I, step 7., of Bell Alert Service Bulletin 429-19-50, Revision B, dated December 19, 2019 (BASB 429-19-50, Revision B). After the inspection, before further flight, do the applicable action required by paragraph (g)(1) or (2) of this AD.
(1) If the lower surface of the spherical bearing is improperly staked (any discrepancy is found e.g., the witness marks are not present and intact or the staked lip is not uniform along the chamfer): Inspect the bore in the bellcrank assembly for excessive wear (including mechanical or corrosion damage that exceed 0.001 inch (0.03 millimeter) maximum depth for 1/4 of the circumference, and any cracking); in accordance with the Accomplishment Instructions, Part I, steps 10. through 13., of BASB 429-19-50, Revision B, and depending on the findings, do the applicable actions required by paragraph (g)(1)(i) or (ii) of this AD before further flight.
(i) If the bore in the bellcrank assembly shows signs of excessive wear: Repair the bellcrank, including re-identifying the bellcrank assembly part number, in accordance with the Accomplishment Instructions, Part II, steps 1. through 13., of BASB 429-19-50, Revision B.
(ii) If the bore diameter is within 0.001 inch (0.03 millimeter) maximum depth for 1/4 of the circumference: Install a new spherical bearing, in accordance with the Accomplishment Instructions, Part II, steps 4. through 12., of BASB 429-19-50, Revision B.
(2) If the lower surface of the spherical bearing is properly staked: Inspect the upper surface of the spherical bearing on the directional control bellcrank assembly to determine if it is properly staked, in accordance with the Accomplishment Instructions, Part I, steps 8. and 9., of BASB 429-19-50, Revision B, and depending on the findings, do the applicable actions required by paragraph (g)(2)(i) or (ii) of this AD before further flight.
(i) If the spherical bearing is properly staked: No further action is required by this AD.
(ii) If the spherical bearing is not properly staked (any discrepancy is found e.g., the witness marks are not present and intact or the staked lip is not uniform along the chamfer): Inspect the bore in the bellcrank assembly for excessive wear (including mechanical or corrosion damage that exceed 0.001 inch (0.03 millimeter) maximum depth for 1/4 of the circumference, and any cracking), in accordance with the Accomplishment Instructions, Part I, steps 10. through 13., of BASB 429-19-50, Revision B, and depending on the findings, do the applicable actions required by paragraph (g)(2)(ii)(A) or (B) of this AD before further flight.
(A) If the bore in the bellcrank assembly shows signs of excessive wear: Repair the bellcrank, including re-identifying the bellcrank assembly part number, in accordance with the Accomplishment Instruction, Part II, steps 1. through 13., of BASB 429-19-50, Revision B.
(B) If the bore diameter is within 0.001 inch (0.03 millimeter) maximum depth for 1/4 of the circumference: Install a new spherical bearing, in accordance with the Accomplishment Instructions, Part II, steps 4. through 12., of BASB 429-19-50, Revision B.
For any helicopter on which the bellcrank has been repaired as required by paragraphs (g)(1)(i) or (g)(2)(ii)(A) of this AD: Within 100 hours TIS after the repair, and thereafter at intervals not to exceed 100 hours TIS, inspect the lower surface of the spherical bearing to determine if it has moved, in accordance with the Accomplishment Instructions, Part III, step 7., of BASB 429-19-50, Revision B. If the spherical bearing has moved (is loose): Before further flight, inspect the bore in the bellcrank assembly to determine if the diameter exceeds 0.6283 inch (15.9588 millimeters), in accordance with the Accomplishment Instructions, Part III, steps 8. through 11., of BASB 429-19-50, Revision B.
(1) If the diameter of the bore in the bellcrank assembly exceeds 0.6283 inch (15.9588 millimeters): Before further flight replace the bellcrank assembly.
(2) If the diameter of the bore in the bellcrank assembly does not exceed 0.6283 inch (15.9588 millimeters): Before further flight install a new spherical bearing in accordance with the Accomplishment Instructions, Part II, steps 4. through 12., of BASB 429-19-50, Revision B.
Replacement of a bellcrank assembly with a new part (never installed on a helicopter or has accumulated zero hours TIS) is terminating action for the requirements of this AD for that helicopter only.
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.
