Airworthiness Directive · Amendment 39-13840 · MD Helicopters, Inc. Model 600N Helicopters
MD Helicopters, Inc. Model 600N Helicopters
Model 600N helicopters, serial numbers with a prefix of “RN” and numbers 025, 029, 032, 034 through 038, 040, 041, 045, 048, or 067; or, any Model 600N helicopter with a yaw stability augmentation system (YSAS) installed, and with a control support bracket assembly, part number (P/N) 369N2608-11, installed, certificated in any category.
This amendment adopts a new airworthiness directive (AD) for MD Helicopters, Inc. Model 600N helicopters that requires replacing the fuselage Station 75 control support bracket assembly (control support bracket), reducing the life limit, and revising the Limitations section of the applicable maintenance manual to state the reduced life limits on certain serial-numbered helicopters. This amendment is prompted by information received from the manufacturer indicating that the fatigue life of the control support bracket is shorter than the original analysis indicated. The actions specified by this AD are intended to prevent failure of the control support bracket and subsequent loss of control of the helicopter.
To prevent failure of the fuselage Station 75 control support bracket assembly (control support bracket) and subsequent loss of control of the helicopter, accomplish the following:
(a) Replace the control support bracket, part number 369N2608-11, with an airworthy control support bracket assembly, P/N 600N2608-1, no later than November 30, 2005, or by the time the helicopter reaches the hours time-in-service (TIS) listed in the chart below, whichever occurs first:
| Helicopter serial number | Revised finite life (TIS) |
|---|---|
| RN025 | 2556 |
| RN029 | 2377 |
| RN032 | 2498 |
| RN034 | 2456 |
| RN035 | 2243 |
| RN036 | 2652 |
| RN037 | 2544 |
| RN038 | 2531 |
| RN040 | 2562 |
| RN041 | 2763 |
| RN045 | 2015 |
| RN048 | 2125 |
| RN067 | 1600 |
Note: MD Helicopters, Inc. Service Bulletin No. SB600N-040, dated September 18, 2003, pertains to the subject of this AD.
(b) For helicopters with a YSAS installed that are not listed in the previous table, replace the control support bracket, P/N 369N2608-11, with an airworthy control support bracket, P/N 600N2608-1, no later than November 30, 2005, or by the time the helicopter reaches 1,600 hours TIS since the installation of the YSAS.
(c) For helicopters with no YSAS installed, but with a control support bracket, P/N 369N26080-11, installed, replace the control support bracket, with an airworthy control support bracket, P/N 600N2608-1, prior to the installation of a YSAS.
(d) This AD revises the Limitations section of the applicable maintenance manual by reducing the life limit of the control support bracket assembly, part number 369N2608-11, to the life limits stated in paragraph (a) of this AD or to 1,600 hours TIS, whichever occurs first.
(e) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Contact the Los Angeles Aircraft Certification Office, Transport Airplane Directorate, FAA, for information about previously approved alternative methods of compliance.
