[Federal Register Volume 62, Number 127 (Wednesday, July 2, 1997)]
[Proposed Rules]
[Pages 35700-35702]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-17258]



[[Page 35700]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-CE-18-AD]
RIN 2120-AA64


Airworthiness Directives; Pilatus Aircraft LTD Models PC-6/B1-H2, 
PC-6/B2-H2, PC-6/B2-H4, and PC-12 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to adopt a new airworthiness directive 
(AD) that would apply to certain Pilatus Aircraft LTD (Pilatus) Models 
PC-6/B1-H2, PC-6/B2-H2, PC-6/B2-H4 airplanes and all Pilatus Model PC-
12 airplanes. The proposed AD would require amending the Limitations 
Section of either the airplane flight manual (AFM) of the pilot's 
operating handbook (POH) to prohibit the positioning of the power 
levers below the flight idle stop while the airplane is in flight. This 
amendment would include a statement of consequences if the limitation 
is not followed. The proposed AD is a result of numerous incidents and 
five documented accidents involving airplanes equipped with turboprop 
engines where the propeller beta was improperly utilized during flight. 
The actions specified by the proposed AD are intended to prevent loss 
of airplane control or engine overspeed with consequent loss of engine 
power caused by the power levers being positioned below the flight idle 
stop while the airplane is in flight.

DATES: Comments must be received on or before September 2, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Central Region, Office of the Assistant Chief 
Counsel, Attention: Rules Docket No. 97-CE-18-AD, Room 1558, 601 E. 
12th Street, Kansas City, Missouri 64106. Comments may be inspected at 
this location between 8 a.m. and 4 p.m., Monday through Friday, 
holidays excepted.
    The AFM revisions referenced in this AD may be obtained from 
Pilatus Aircraft Ltd., CH-6370 Stans, Switzerland. This information 
also may be examined at the Rules Docket at the address above.

FOR FURTHER INFORMATION CONTACT: J. Mike Kiesov, Aerospace Engineer, 
FAA, Small Airplane Directorate, 1201 Walnut, suite 900, Kansas City, 
Missouri 64106; telephone (816) 426-6934; facsimile (816) 426-2169.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed 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 above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed 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 proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket No. 97-CE-18-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Central Region, Office of the Assistant Chief Counsel, 
Attention: Rules Docket No. 97-CE-18-AD, Room 1558, 601 E. 12th Street, 
Kansas City, Missouri 64106.

Discussion

    The FAA has received reports of 14 occurrences in recent years of 
incidents or accidents on airplanes equipped with turboprop engines 
related to intentional or inadvertent operation of the propellers in 
the beta range during flight. Beta is the range of propeller operation 
intended for use during taxi, ground idle, or reverse operations as 
controlled by the power lever settings aft of the flight idle stop.
    Of the 14 documented in-flight beta occurrences, five were 
classified as accidents. In-flight beta operation results that preceded 
the accidents can be classified in one of two categories: (1) Permanent 
engine damage and total loss of thrust on all engines when the 
propeller that was operating in the beta range drove the engines to 
overspeed; and (2) loss of airplane control because at least one 
propeller operated in the beta range during flight.
    The most recent accident occurred when both engines of a Saab Model 
340B permanently lost power after eight seconds of beta range propeller 
operation. The propellers consequently drove the engines into 
overspeed, which resulted in internal engine failure.
    Communication between the FAA and the public during a meeting held 
on June 11-12, 1996, in Seattle, Washington, revealed a lack of 
consistency of the information on in-flight beta operation contained in 
the airplane flight manual (AFM) for airplanes not certificated for in-
flight operation with the power levers below the flight idle stop. 
Airplanes that are certificated for this type of operation are not 
affected by the above-referenced conditions.

Applicable Service Information

    Pilatus has issued the following revisions to the affected 
airplanes' AFM or POH:

--Temporary Revision To Pilatus/PC-6 B1 and B2 Series Airplanes Flight 
Manuals; Section 1; Certificate Limitations; Issued: November 29, 1996; 
and
--Temporary Revision To PC-12 Pilot's Operating Handbook; Pilatus 
Report No. 01973-001, dated November 20, 1996.

The FAA's Determination

    After examining the circumstances and reviewing all available 
information related to the incidents and accidents referenced above, 
including the temporary revisions to the AFM or POH, the FAA has 
determined that:
     All airplanes equipped with turboprop engines (provided 
the airplane is not certificated for in-flight operation with the power 
levers below the flight idle stop) should have information in the 
Limitations Section of the AFM that prohibits positioning of power 
levers below the flight idle stop while the airplane is in flight, 
including a statement of consequence if the limitation is not followed; 
and
     Because Pilatus Models PC-6/B1-H2, PC-6/B2-H2, PC-6/B2-H4 
airplanes that are equipped with a Pratt and Whitney PT6A turboprop 
engine and Pilatus Model PC-12 airplanes equipped with turboprop 
engines are not certificated for in-flight operation with the power 
levers below the flight idle stop, and do not contain information in 
the Limitations Section

[[Page 35701]]

of the AFM or POH that prohibits and explains the consequences of such 
operation, AD action should be taken. The proposed AD is intended to 
prevent loss of airplane control or engine overspeed with consequent 
loss of engine power caused by the power levers being positioned below 
the flight idle stop while the airplane is in flight.

Explanation of the Provisions of the Proposed AD

    Since an unsafe condition has been identified that is likely to 
exist or develop in other Models PC-6/B1-H2, PC-6/B2-H2, PC-6/B2-H4 
airplanes and PC-12 series airplanes of the same type design, the 
proposed AD would require amending the Limitations Section of the AFM 
or POH to prohibit the positioning of the power levers below the flight 
idle stop while the airplane is in flight, including a statement of 
consequences if the limitation is not followed. Amending the AFM or POH 
would be accomplished by inserting the Temporary AFM or POH revisions 
previously referenced.

Compliance Time of the Proposed AD

    The FAA has determined that the compliance time of the proposed AD 
should be specified in calendar time instead of hours time-in-service. 
While the condition addressed by the proposed AD is unsafe while 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 
proposed compliance time of ``30 days after the effective date of this 
AD'' would not inadvertently ground airplanes and would assure that all 
owners/operators of the affected airplanes accomplish the proposed 
action in a reasonable time period.

Cost Impact

    The FAA estimates that 72 airplanes in the U.S. registry would be 
affected by the proposed AD, that it would take approximately 1 
workhour per airplane to incorporate the proposed AFM amendment, and 
that the average labor rate is approximately $60 an hour. Since an 
owner/operator who holds at least a private pilot's certificate as 
authorized by sections 43.7 and 43.11 of the Federal Aviation 
Regulations (14 CFR 43.7 and 43.11) can accomplish the proposed action, 
the only cost impact upon the public is the time it would take the 
affected airplane owner/operators to amend the AFM or POH.

Regulatory Impact

    The regulations proposed herein would 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 
proposal would 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) if promulgated, 
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 draft regulatory evaluation 
prepared for this action has been placed 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.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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.


Sec. 39.13  [Amended]

    Section 39.13 is amended by adding a new airworthiness directive 
(AD) to read as follows:

Pilatus Aircraft Ltd: Docket No. 97-CE-18-AD.

    Applicability: The following model and serial number airplanes, 
certificated in any category:

--Model Pilatus Models PC-6/B1-H2, PC-6/B2-H2, PC-6/B2-H4 airplanes, 
all serial numbers, that are equipped with a Pratt and Whitney PT6A 
turboprop engine.
--Model Pilatus PC-12 airplanes, all serial numbers.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes 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 (d) 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.

    Compliance: Required within the next 30 days after the effective 
date of this AD, unless already accomplished.
    To prevent loss of airplane control or engine overspeed with 
consequent loss of engine power caused by the power levers being 
positioned below the flight idle stop while the airplane is in 
flight, accomplish the following:
    (a) Amend the Limitations Section of the airplane flight manual 
(AFM) or pilot's operating handbook (POH) by inserting the following 
revisions, as applicable:
    (1) Temporary Revision To Pilatus/PC-6 B1 and B2 Series 
Airplanes Flight Manuals; Section 1; Certificate Limitations; 
Issued: November 29, 1996;
    (2) Temporary Revision To PC-12 Pilot's Operating Handbook; 
Pilatus Report No. 01973-001, dated November 20, 1996.
    (b) Amending the AFM or POH, as required by 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 this AD in accordance with section 
43.11 of the Federal Aviation Regulations (14 CFR 43.11).
    (c) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.
    (d) An alternative method of compliance or adjustment of the 
compliance time that provides an equivalent level of safety may be 
approved by the Manager, Small Airplane Directorate, FAA, 1201 
Walnut, Kansas City, Missouri 64106. The request shall be forwarded 
through an appropriate FAA Maintenance Inspector, who may add 
comments and then send it to the Manager, Small Airplane 
Directorate.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Small Airplane Directorate.

    (e) The AFM or POH revisions referenced in this AD may be 
obtained from Pilatus Aircraft Ltd., CH-6370 Stans, Switzerland. 
Information related to this AD may be examined at the FAA, Central 
Region, Office of the Assistant Chief Counsel, Room 1558, 601 E. 
12th Street, Kansas City, Missouri 64106.


[[Page 35702]]


    Issued in Kansas City, Missouri, on June 25, 1997.
James E. Jackson,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-17258 Filed 7-1-97; 8:45 am]
BILLING CODE 4910-13-U