This amendment adopts a new airworthiness directive (AD) applicable to MDHI Model 369D, 369E, 500N, and 600N helicopters with certain analog/digital TOT indicators installed. This action requires repetitive testing of the TOT indicating system to verify correct calibration and to take corrective actions if necessary. This amendment is prompted by seven reports of erroneous TOT readings, up to 100 degrees Celsius low. This amendment is also prompted by two reports of incorrect wiring harness terminal lugs on the thermocouple wiring. Reports indicated that some of the TOT readings did not agree with the engine Electronic Control Unit (ECU) and some readings were found to be 4 degrees Celsius to 17 degrees Celsius low. The actions specified in this AD are intended to prevent erroneous TOT indications, which could prevent the flight crew from detecting that an engine temperature limitation has been exceeded. This condition, if not corrected, could resultin damage to critical engine components, loss of engine power, and a subsequent forced landing.
The FAA has reviewed MDHI Service Bulletins SB369D-199, SB369E-093, SB500N-019 (for Model 369D, 369E, and 500N helicopters) and SB600N-026 (for Model 600N helicopters), both dated January 11, 2000. These service bulletins describe procedures for calibration testing of the TOT indicating system and corrective actions if necessary. The corrective actions include inspecting TOT wire harness terminal lugs, connector pins, and sockets to verify correct material and installation; retesting the TOT indicating system; and replacing any unairworthy part with an airworthy part. For Model 600N helicopters, Part III of the service bulletin also describes procedures for verifying the electronic control unit (ECU) TOT calibration.
Since an unsafe condition has been identified that is likely to exist or develop on other MDHI model helicopters of these same type designs, this AD is being issued to prevent an erroneous TOT indication, damage to critical engine components, loss of engine power, and a subsequent forced landing. The actions are required to be accomplished in accordance with the service bulletins described previously, except as discussed in the following paragraphs. The short compliance time involved is required because the previously described critical unsafe condition can adversely affect the engine, causing a loss of engine power and a subsequent forced landing of the helicopter. Therefore, initial testing of the TOT indicating system to verify correct calibration is required within the next 50 hours time-in-service (TIS) or on or before June 15, 2000, whichever occurs earlier, and this AD must be issued immediately.
This AD is an interim action. The manufacturer has advised that it currently is developing a modification that will permanently address the unsafe condition.
The service bulletins specify certain serial numbered helicopters with theaffected analog/digital TOT indicator installed. The FAA has determined that any Model 369D, 369E, 500N, and 600N helicopter may have the analog/digital TOT indicator, part number (P/N) 369D24513-1 or P/N 9A3420, installed, since the helicopter manufacturer has not developed a modification to correct the unsafe condition. Even subsequently manufactured Model 369D, 369E, 500N, and 600N helicopters may have these analog/digital TOT indicators installed.
The service bulletins recommend accomplishing the TOT system calibration test within 100 hours TIS. The FAA has determined that a 100-hour TIS compliance time would not address the unsafe condition in a timely manner. In developing an appropriate compliance time for this AD, the FAA considered not only the manufacturer's recommendation, but the degree of urgency associated with addressing the unsafe condition, the average utilization of the affected fleet, and the time necessary to perform the test. In light of all these factors, the FAA finds a compliance time within the next 50 hours TIS or on or before June 15, 2000, whichever occurs first, for initiating the required test is an appropriate interval of time that affected helicopters can operate without compromising safety.
Additionally, the FAA has determined that long-term continued operational safety will be better assured by repetitive testing of the TOT indicating system at intervals not to exceed 300 hours TIS, rather than a one- time test, because of reports that the system calibration may shift with service time. A one-time test may not provide the degree of safety assurance necessary to ensure that the TOT indicator is properly calibrated over time.
Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.
The FAA estimates that 566 helicopters will be affected by this proposed AD, that it will take approximately 0.5 work hour to accomplish the test, and that the average labor rate is $60 per work hour. The manufacturer has represented in the service bulletins that parts will be provided at no cost to the operator. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $16,980, per test cycle for the entire fleet.
Comments Invited
Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.
Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their mailed comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket No. 2000-SW-02-AD." Thepostcard will be date stamped and returned to the commenter.
The regulations adopted herein will not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132.
The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES."
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:
PART 39 - AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive to read as follows: