Airworthiness Directive · Amendment 39-17386 · Main rotor mast/swashplate
Bell Helicopter Textron, Inc.
This AD applies to Bell Model 412 and 412EP helicopters, with a swashplate outer ring assembly (outer ring), part number (P/N) 412-010-407-105, certificated in any category.
We are adopting a new airworthiness directive (AD) for Bell Helicopter Textron, Inc. (Bell), Model 412 and 412EP helicopters. This AD requires establishing a lower life limit on certain swashplate outer ring assemblies (outer ring), revising the retirement life on the components' history card or equivalent record, and revising the maintenance manual or Instructions for Continued Airworthiness (ICA). This AD also prohibits installing these outer rings on any helicopter. This AD was prompted by reports of cracking in the outer rings. The actions are intended to prevent failure of an outer ring because of cracking, which could lead to the loss of main rotor (M/R) blade pitch control and subsequent loss of helicopter control.
You are responsible for performing each action required by this AD within the specified compliance time unless it has already been accomplished prior to that time.
(1) Within 30 days, establish a retirement life of 2,500 hours time-in-service (TIS) for any affected outer ring on the component history card or equivalent record. Revise the helicopter Airworthiness Limitations section of the applicable maintenance manual or Instructions for Continued Airworthiness (ICA) by establishing the new retirement life by making pen-and-ink changes or inserting a copy of this AD into the maintenance manual or the ICAs.
(2) For any affected outer ring that, on the effective date of this AD, has 2,200 or more hours TIS, within 300 hours TIS, replace the outer ring with an airworthy outer ring.
(3) Within 12 months, for any affected outer ring, regardless of the number of hours TIS, replace the outer ring with an airworthy outer ring.
(4) Do not install outer ring, P/N 412-010-407-105, on any helicopter.
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.
