Airworthiness Directive · Amendment 39-11708 · MD Helicopters Inc. Model 369D, 369E, 500N, and 600N Helicopters
MD Helicopters Inc. Model 369D, 369E, 500N, and 600N Helicopters
Model 369D, 369E, and 500N helicopters, with analog/digital turbine outlet temperature (TOT) indicator, part number (P/N) 369D24513-1, installed; and Model 600N helicopters, with analog/digital TOT indicator, P/N 9A3420, installed; certificated in any category.
Note 1: This AD applies to each helicopter identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For helicopters that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (f) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.
This amendment adopts a new airworthiness directive (AD) applicable to MD Helicopters Inc. (MDHI) Model 369D, 369E, 500N, and 600N helicopters with certain analog/digital turbine outlet temperature (TOT) indicators installed. This action requires repetitive calibration testing of the TOT indicating system and corrective actions if necessary. This amendment is prompted by seven reports of erroneous TOT readings and two reports of incorrect wiring harness terminal lugs on the thermocouple wiring. The actions specified in this AD are intended to prevent an erroneous TOT indication, damage to critical engine components, loss of engine power, and a subsequent forced landing.
To prevent an erroneous TOT indication, damage to critical engine components, loss of engine power, and a subsequent forced landing, accomplish the following:
(a) For Model 369E, 369D, and 500N helicopters: Within the next 50 hours time-in-service (TIS) or on or before June 15, 2000, whichever occurs first; test the TOT indicating system to verify correct calibration in accordance with the Accomplishment Instructions, Part I, of MD Helicopters, Inc. (MDHI) Service Bulletin SB369D-199, SB369E-093, SB500N-019, dated January 11, 2000 (SB). Thereafter, repeat the test at intervals not to exceed 300 hours TIS.
(b) If during any test required by paragraph (a) of this AD the TOT indicator readings for the tester setting temperatures in Table 1, Part I, of the SB are not within the indicator reading range, before further flight, perform the actions in the Accomplishment Instructions, Part I, paragraph (6)(b) of the SB.
(c) For Model 600N helicopters: Within the next 50 hours TIS or on or before June 15, 2000, whichever occurs first; test the TOT indicating system, including the electronic control unit (ECU) TOT sensing system, to verify correct calibration in accordance with the Accomplishment Instructions, Part I, of MDHI SB600N-026, dated January 11, 2000 (SB 600N). Thereafter, repeat the test at intervals not to exceed 300 hours TIS.
(d) If during any calibration test required by paragraph (c) of this AD the TOT indicator readings for the tester setting temperatures in Table 1, Part I, of SB 600N, are not within the indicator reading range, before further flight, perform the actions in the Accomplishment Instructions, Part I, paragraph (7)(b) of SB 600N.
(e) If during any test required by paragraph (c) of this AD the Full Authority Digital Electronic Control (FADEC) maintenance lap-top terminal does not indicate ECU TOT within (5 degrees Celsius of the tester setting in Table 1, Part I, of SB 600N, before further flight, perform the actions in the Accomplishment Instructions, Part III, of the SB 600N.
