Events Leading to the Issuance of This AD
A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to all de Havilland Models DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-300 airplanes was published in the Federal Register as a notice of proposed rulemaking (NPRM) on October 22, 1998. The NPRM proposed to require amending the Limitations Section of the AFM to prohibit the positioning of the power levers aft of the flight idle stop while the airplane is in flight, including a statement of consequences if the limitation is not followed. This AFM amendment shall consist of the following language:
"Positioning of power levers aft of the flight idle stop while the airplane is in flight is prohibited. Such positioning may lead to loss of airplane control or may result in an overspeed condition and consequent loss of engine power."
The NPRM was the result of numerous incidents and five documented accidents involving airplanes equipped with turboprop engines where the propeller beta was improperly utilized during flight. None of the incidents or accidents involved de Havilland Inc. Models DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-300 airplanes.
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the one comment received.
Comment Disposition
The commenter supports the AD as written and believes that the FAA should issue additional AD action that mandates a modification that would prevent the flight crews from intentionally or inadvertently selecting the power levers below the flight idle stop while in flight. The commenter suggests this modification be in the form of a mechanical lockout device to preclude such power lever selection.
The FAA is currently evaluating each of the aircraft where AD s were issued to address this issue with a flight manual revision. The purposeof this evaluation is to determine whether a mechanical lockout device is necessary. Among those aircraft the FAA is evaluating are the de Havilland DHC-6 series airplanes. If the FAA determines that such a device is necessary, additional rulemaking may be initiated. No changes have been made to the final rule as a result of this comment.
The FAA's Determination
After careful review of all available information related to the subject presented above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed except for minor editorial corrections. The FAA has determined that these minor corrections will not change the meaning of the AD and will not add any additional burden upon the public than was already proposed.
Compliance Time of This AD
The FAA has determined that the compliance time of this AD will be specified in calendar time instead of hours time-in-service. While the condition addressed by this AD is unsafewhile the airplane is in flight, the condition is not a result of repetitive airplane operation; the potential of the unsafe condition occurring is the same on the first flight as it is for subsequent flights. The compliance time of "30 days after the effective date of this AD" will not inadvertently ground airplanes and will assure that all owners/operators of the affected airplanes accomplish this action in a reasonable time period.
Cost Impact
The FAA estimates that 114 airplanes in the U.S. registry will be affected by this AD, that it will take approximately 1 workhour per airplane to incorporate the AFM amendment, and that the average labor rate is approximately $60 an hour. Accomplishing the AFM revision requirements of this AD may be performed by the owner/operator holding at least a private pilot certificate as authorized by section 43.7 of the Federal Aviation Regulations (14 CFR 43.7), and must be entered into the aircraft records showing compliance with the AD inaccordance with section 43.9 of the Federal Aviation Regulations (14 CFR 43.9). The only cost impact of this AD is the time it would take each owner/operator of the affected airplanes to insert the information into the AFM.
Regulatory Impact
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 copy of the final evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption "ADDRESSES".
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, 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 (AD) to read as follows: