Discussion
What events have caused this AD?: The FAA has received two reports of engine power turbine failures on Raytheon Beech Model 65-A90 airplanes. Each of these airplanes had the original Pratt & Whitney PT6A-20 turboprop engines replaced with Motorlet, Walter M601E-11 turboprop engines (with Avia-Hamilton Standard VJ8-510 propellers). Supplemental Type Certificate (STC) SA01366AT contains the approval and procedures for this replacement. One of the engine failures was uncontained and one resulted in engine seizure on the opposite engine.
Investigation of the incidents is ongoing; however, the FAA has identified several installation discrepancies. Among these are:
- the engine control electronic limiters (governors) were not installed. This system lowers the fuel delivery and, thus protects the engine against over-temperature at startup and overspeed at BETA control and reverse rating. This could result in engine failure due to overspeed and/or turbine over-temperature conditions;
- the required propeller de-icing system was not installed;
- the propeller feathering pump was not installed, which could prevent feathering of the propeller in the event of an engine seizure; and
- the cabin supercharger was not installed in a manner to assure proper pressurization of the aircraft.
What are the consequences if the condition is not corrected?: These discrepancies, if not corrected, could lead to engine failure and the inability to feather the propeller. This could result in an uncontained engine failure with consequent loss of control of the airplane.
The FAA's Determination and an Explanation of the Provisions of the AD
What has the FAA decided?: After examining the circumstances and reviewing all available information related to the incidents described above, including the relevant service information, the FAA has determined that:
- an unsafe condition exists or could develop on RaytheonBeech Models 65-90, 65-A90, B90, and C90 airplanes of the same type design (to the airplanes referenced above) that incorporate STC SA01366AT; and
- AD action should be taken in order to prevent an uncontained engine failure due to suspect engine and propeller installation, which could result in loss of control of the airplane.
What does this AD require?: This AD prohibits you from operating any affected airplane with STC SA01366AT incorporated and prohibits you from incorporating this STC in the future.
What is the compliance time of this AD?: The compliance time of both the operations and installation prohibition is "as of the effective date of this AD." Will this compliance time inadvertently ground airplanes?: No. The only 2 airplanes that currently incorporate the configuration of the affected STC were involved in the referenced incidents. The engines of these airplanes will be replaced in accordance with the original type certificate data sheet (TCDS) or otherFAA-approved STC. Basically, this AD prevents future installation of the configuration specified in STC SA01366AT.
Will the public have the opportunity to comment prior to the issuance of the rule?: No. Since a situation exists (possible uncontained engine failure) that requires the immediate adoption of this regulation, the FAA has determined that notice and opportunity for public prior comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.
Comments Invited
Although this action is in the form of a final rule and was not preceded by notice and opportunity for public comment, the FAA invites comments on this rule. You may submit whatever written data, views, or arguments you choose. You need to include the rule's docket number and submit your comments in triplicate to the address specified under the caption "ADDRESSES." The FAA will consider all comments received on or before the closing date. We may amendthis rule in light of comments received. Factual information that supports your ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether we need to take additional rulemaking action.
The FAA is re-examining the writing style we currently use in regulatory documents, in response to the Presidential memorandum of June 1, 1998. That memorandum requires federal agencies to communicate more clearly with the public. We are interested in your comments on whether the style of this document is clearer, and any other suggestions you might have to improve the clarity of FAA communications that affect you. You can get more information about the Presidential memorandum and the plain language initiative at http://www.plainlanguage.gov.
The FAA specifically invites comments on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. You may examine all comments we receive before and after the closing date of the rule in the Rules Docket. We will file a report in the Rules Docket that summarizes each FAA contact with the public that concerns the substantive parts of this AD.
If you want us to acknowledge the receipt of your comments, you must include a self-addressed, stamped postcard. On the postcard, write "Comments to Docket No. 99-CE-92-AD." We will date stamp and mail the postcard back to you.
Regulatory Impact
These regulations 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, the FAA has 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 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 (otherwise, an evaluation is not required). A copy of it, if filed, may be obtained from the Rules Docket.
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: