Airworthiness Directive · Amendment 39-17619 · Turbine section
Bell Helicopter Textron Canada Limited (Bell) Helicopters
Superseded. A later AD replaced this one: AD 2021-11-01. Comply with the one in force.
This AD applies to the following helicopters, certificated in any category:
(1) Bell Model 206B, serial number (S/N) 004 through 4675, including helicopters converted from Model 206A; and
(2) Bell Model 206L, S/N 45001 through 45153, and 46601 through 46617.
We are adopting a new airworthiness directive (AD) for certain Bell Model 206B and 206L helicopters. This AD requires installing a placard beneath the engine power dual tachometer and revising the operating limitations section of the rotorcraft flight manual (RFM). This AD was prompted by several incidents of third stage engine turbine wheel failures, which were caused by excessive vibrations at certain engine speeds during steady-state operations. These actions are intended to alert pilots to avoid certain engine speeds during steady- state operations, prevent failure of the third stage engine turbine, engine power loss, and subsequent loss of control of the helicopter.
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.
Within 30 days:
(1) For Model 206B helicopters:
(i) Revise the Operating Limitations section of the Model 206B Rotorcraft Flight Manual (RFM) by inserting Section 1, Operating Limitations, page 1-2A, of Bell BHT-206B-FM-1, revision B-50, dated December 8, 2008.
(ii) Remove placard part number (P/N) 230-075-213-121, if installed.
(iii) Install placard P/N 230-075-213-125, or equivalent, on the instrument panel directly below the dual tachometer.
(2) For Model 206L helicopters:
(i) Revise the Operating Limitations section of the Model 206L RFM by inserting Section 1, Operating Limitations, page 1-4B, of Bell BHT-206L-FM-1, revision 28, dated December 8, 2008.
(ii) Remove placard P/N 230-075-213-123, if installed.
(ii) Install placard P/N 230-075-213-127, or equivalent, on the instrument panel below the dual tachometer.
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.
