AD 97-15-10

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to AlliedSignal Inc. TPE331 series turboprop engines equipped with Woodward fuel controls was published in the Federal Register on October 3, 1996 (61 FR 51618). That action proposed to require revising the Abnormal Procedures or Emergency Procedures Section of the applicable Federal Aviation Administration (FAA) approved Airplane Flight Manual (AFM) or Pilot's Operating Handbook (POH) to include a paragraph relating to a non-responsive power lever. In addition, the notice proposed requiring replacing orifice fittings and reworking restrictors, which would constitute terminating action to the requirement to revise the applicable AFM or POH.

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the single comment received.

The commenter states that the Ayres S2R series aircraft should be removed from the AD applicability. The commenter states that the Ayres aircraft models are certified for Visual Flight Rules (VFR) operations at 12,000 feet or below, and are not normally operated in the altitude and temperature environment described in the AD. In addition, the engine has no anti-ice capability installed in this airplane. Also, the commenter is not aware of any reports of "no response to power lever movement" regarding this airplane. The FAA does not concur. First, the AD will apply to all TPE331-3, -5, -6, -10, -11, and -12 engines equipped with Woodward fuel controls, regardless of what aircraft those engines are installed on. The list of aircraft is provided for informational purposes only and is not an exclusive listing of aircraft on which operators might find the affected engines. In addition, the FAA is aware that some aircraft may be configured without anti-ice capability, and, therefore, no action would be required under paragraph (a), which addresses engines installed on aircraft with engine inlet ice protection. However, the FAA considers engines without engine anti-ice capability within the scope of the unsafe condition described in this AD and therefore, must be modified in accordance with paragraph (b) or (c) of the AD.

Also, the FAA has considered that no reports were submitted regarding "no response to power lever movement" for the Ayres series aircraft and that the maximum operating altitude for these aircraft is 12,000 feet. Even though ice blockage of the PT2 sensor and pressure signal increase is an infrequent phenomena and may be influenced by engine installation, flight operation, and environmental factors, the FAA has decided to implement the engine orifice fitting and restrictor modifications based on engine design similarity and the possibility that the sensor can ice up at lower altitudes in clear air given the right combination of temperature, relative humidity and airspeed. Therefore, the Ayres series aircraft will remain in the AD applicability.

The FAA has determined that the paragraphs (b) and (c) of the compliance section might be read ambiguously and that both paragraphs would have to be complied with when the intent is that engines affected by AlliedSignal Aerospace Service Bulletin (SB) No. TPE331-73-0235, dated July 28, 1995, must comply with paragraph (b) and engines affected by AlliedSignal Aerospace SB No. TPE331-73-0236, dated July 28, 1995, must comply with paragraph (c). The FAA has revised the compliance section of this final rule accordingly to clear up the possible ambiguity. After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes described previously. The FAA has determined that these changes will neither increase the economic burden on any operator nor increasethe scope of the AD.

There are approximately 9,438 engines of the affected design in the worldwide fleet. The FAA estimates that 4,700 engines installed on aircraft of U.S. registry will be affected by this AD. The FAA estimates that 2,760 engines will need modification in accordance with AlliedSignal Aerospace SB No. TPE331-73-0236, dated July 28, 1995, that it will take approximately 2 work hours per engine to accomplish the proposed actions, and that the average labor rate is $60 per work hour. Required parts will cost approximately $80 per engine.

In addition, the FAA estimates that 1,240 engines will need modification in accordance with AlliedSignal Aerospace SB No. TPE331-73-0235, dated July 28, 1995, that it will take approximately 3 work hours per engine to accomplish the proposed actions, and that the average labor rate is $60 per work hour. Required parts will cost approximately $80 per engine. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $874,400.

The regulations adopted herein will not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A final evaluation has been prepared for this action and it is contained in the Rules Docket.A copy of it 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 the following new airworthiness directive: