Airworthiness Directives; Pratt & Whitney Canada PW100 Series Turboprop Engines

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 93-ANE-47; Amendment 39-8927; AD 94-11-11]

Airworthiness Directives; Pratt & Whitney Canada PW100 Series

Turboprop Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes an existing airworthiness directive

(AD), applicable to Pratt & Whitney Canada PW100 series turboprop

engines, that currently requires rework or replacement of the

intercompressor case (ICC), and replacement of the low pressure rotor

speed (NL) sensor port sealing tube and the external air tube

connecting the P2.5/P3 switching valve to the rear inlet case. This

amendment additionally requires installation of an airflow deflector

bracket nozzle assembly, or modification of the No. 5 bearing pressure

air system. Finally, this action requires installation of a No. 5

bearing vent tube assembly and allows extension of the compliance

interval for reworking or replacing the ICC. This amendment is prompted

by the development of additional hardware that will further reduce the

risk of internal oil fires in the ICC. The actions specified by this AD

are intended to prevent fire in the engine ICC and nacelle cavities,

inflight engine shutdown, and aircraft damage.

DATES: Effective July 25, 1994.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of July 25, 1994.

ADDRESSES: The service information referenced in this AD may be

obtained from Pratt & Whitney Canada, Technical Publications

Department, 1000 Marie Victorin, Longueuil, Quebec J4G 1A1. This

information may be examined at the Federal Aviation Administration

(FAA), New England Region, Office of the Assistant Chief Counsel, 12

New England Executive Park, Burlington, MA 01803-5299; or at the Office

of the Federal Register, 800 North Capitol Street, NW., suite 700,

Washington, DC.

FOR FURTHER INFORMATION CONTACT: Marc Bouthillier, Aerospace Engineer,

Engine Certification Office, FAA, Engine and Propeller Directorate, 12

New England Executive Park, Burlington, MA 01803-5299; telephone (617)

238-7135, fax (617) 238-7199.

SUPPLEMENTARY INFORMATION: Transport Canada, which is the airworthiness

authority for Canada, recently notified the Federal Aviation

Administration (FAA) that an unsafe condition may exist on Pratt &

Whitney Canada (PWC) PW118A, PW123, PW124B, PW125B, and PW126A

turboprop engines. Transport Canada advises that they have received

reports of internal oil fires in the intercompressor case (ICC). There

have been 13 ICC fire events due to ignition of oil that had

accumulated in the P2.5 air cavity. The ICC fire melts the brazing on

the external air-tube connected to the P2.5/P3 switching-valve, and on

the low pressure rotor speed (NL) sensor port sealing tube, allowing

both to disengage. The ICC fire then migrates into the engine nacelle

cavity resulting in inflight engine shutdown and potential aircraft

damage.

On December 14, 1992, the FAA issued AD 92-22-01, Amendment 39-8387

(58 FR 6191, January 27, 1993), to require rework or replacement of the

existing ICC and replacement of the NL sensor port sealing tube and the

external air tube connecting the P2.5/P3 switching valve to the rear

inlet case.

Since the issuance of that AD, the manufacturer has developed

additional hardware that will further reduce the risk of internal oil

fires in the ICC.

A proposal to supersede AD 92-22-01 was published in the Federal

Register on November 3, 1993 (58 FR 58669). That action proposed to

retain the requirements for rework or replacement of the existing ICC

and replacement of the NL sensor port sealing tube and the external air

tube connecting the P2.5/P3 switching valve to the rear inlet case.

That action also proposed to extend the compliance end date for rework

or replacement of the December 31, 1995, based upon fleet utilization

rates and parts availability. In addition, that action proposed to

require installation of an airflow deflector bracket nozzle assembly,

or modification of the No. 5 bearing pressure air system. Finally, that

action proposed to require installation of a No. 5 bearing vent tube

assembly.

PWC has issued the following service bulletins (SB): SB No. 21112,

dated February 13, 1992; SB No. 20914, Revision 3, dated October 15,

1991; SB No. 21113, Revision 1, dated May 4, 1992; SB No. 21111,

Revision 1, dated June 22, 1992; SB No. 21088, Revision 1, dated

November 12, 1991; and SB No. 21097, dated November 8, 1991. These SB's

describe procedures for replacing the NL sensor port sealing tube and

the external air tube connecting the P2.5/P3 switching valve to the

rear inlet case.

In addition, PWC has issued the following SB's: SB No. 20957,

Revision 5, dated August 10, 1992, and SB No. 20962, Revision 4, dated

August 10, 1992, that describe procedures for reworking the existing 2

hole internal air passage ICC to a 19 hole design.

PWC has also issued the following SB's: SB No. 21065, Revision 4,

dated February 1, 1993, that describes procedures for installing an

airflow deflector bracket nozzle assembly; SB No. 21211, dated January

28, 1993, that describes procedures for modifying the No. 5 bearing

pressure air system; and SB No. 21053, Revision 2, dated December 9,

1991, that describes procedures for installing a No. 5 bearing vent

tube assembly.

This engine model is manufactured in Canada and is type

certificated for operation in the United States under the provisions of

Section 21.29 of the Federal Aviation Regulations and the applicable

bilateral airworthiness agreement. Pursuant to this bilateral

airworthiness agreement, Transport Canada has kept the FAA informed of

the situation described above. Transport Canada issued AD's No. CF-91-

26R1, CF-92-03R1, and CF-92-06, mandating the accomplishment of the

above service bulletins. The FAA has examined the findings of Transport

Canada, reviewed all available information, and determined that AD

action is necessary for products of this type design that are

certificated for operation in the United States.

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the comments received.

One commenter offered no objection to the proposed rule.

One commenter states that earlier revisions to the SB's listed in

the proposed rule should be acceptable for compliance, as the revisions

were minor and did not materially affect the AD's requirements. The FAA

concurs. PWC has issued PW100 Service Information Letter (SIL) No. PW-

281 that lists those SB's and revision levels that constitute

acceptable methods of compliance to the actions required by this AD.

The FAA has added a note to paragraph (f) of the AD to provide further

guidance to operators on those acceptable alternate methods of

compliance.

One commenter states that the economic analysis in the proposed

rule significantly underestimated costs to operators, by not including

the costs for premature engine removal, added inspections and parts

replacement not required by the proposed rule but required by the

applicable maintenance manuals, and for life limited parts not suitable

for reinstallation. The FAA does not concur. While other costs may be

involved, they represent costs that will be borne by the operators

eventually anyway. The economic analysis examines only those costs

directly related to the actions required by the proposed rule. Although

the AD may result in a hot section inspection at a time earlier than

the operator originally scheduled, the costs of that inspection are not

directly related to the requirements of the AD, and therefore are not a

result of the AD. In addition, those costs will vary significantly for

each engine, and, may not be accurate if extrapolated to a fleet-wide

estimate based on a small sampling.

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 change described

previously. The FAA has determined that this change will neither

increase the economic burden on any operator nor increase the scope of

the AD.

The FAA estimates that 85 engines installed on aircraft of U.S.

registry will be affected by this AD, that it will take approximately 8

work hours per engine to accomplish the required actions, and that the

average labor rate is $55 per work hour. The manufacturer advises the

FAA that required parts will be supplied 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 $37,400.

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 14 CFR part

39 of the Federal Aviation Regulations as follows:

PART 39--AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.

106(g); and 14 CFR 11.89.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing amendment 39-8387 (58 FR

6191, January 27, 1993) and by adding a new airworthiness directive,

Amendment 39-8927, to read as follows:

94-11-11 Pratt & Whitney Canada: Amendment 39-8927.

Docket 93-ANE-47. Supersedes AD 92-22-01, Amendment 39-8387.

Applicability: Pratt & Whitney Canada (PWC) PW118A, PW123, PW124B,

PW125B, and PW126A turboprop engines installed on but not limited to

Embraer EMB-120, DeHavilland Dash 8 Series 300, Aerospatiale ATR 72,

Fokker 50, and British Aerospace ATP aircraft.

Compliance: Required as indicated, unless accomplished previously.

To prevent fire in the engine intercompressor case (ICC) and

nacelle cavities, inflight engine shutdown, and aircraft damage,

accomplish the following:

(a) Replace the low pressure rotor speed (NL) sensor port sealing

tube and the external air tube connecting the P2.5/P3 switching valve

to the rear inlet case at the next engine shop visit, but not later

than October 21, 1994, 120 days after the date of publication in the

Federal Register as follows:

(1) For PW118A engines, in accordance with PWC Service Bulletin

(SB) No. 21112, dated February 13, 1992, and SB No. 20914, Revision 3,

dated October 15, 1991.

(2) For PW123 engines, in accordance with PWC SB No. 21113,

Revision 1, dated May 4, 1992.

(3) For PW124B engines, in accordance with PWC SB No. 21111,

Revision 1, dated June 22, 1992.

(4) For PW125B engines, in accordance with PWC SB No. 21088,

Revision 1, dated November 12, 1991.

(5) For PW126A engines, in accordance with PWC SB No. 21097, dated

November 8, 1991.

(b) Install an airflow deflector bracket nozzle assembly in

accordance with PWC SB No. 21065, Revision 4, dated February 1, 1993,

or modify the No. 5 bearing pressure air system in accordance with SB

21211, dated January 28, 1993, at the next engine shop visit, but not

later than December 31, 1995.

(c) Install a No. 5 bearing vent tube assembly in accordance with

PWC SB No. 21053, Revision 2, dated December 9, 1991, at the next

engine shop visit, but not later than December 31, 1995.

(d) For engines incorporating the modifications specified by any

revision level of PWC SB No. 20237, rework the existing 2 hole internal

air passage ICC to a 19 hole design, or replace the existing ICC, in

accordance with PWC SB No. 20957, Revision 5, dated August 10, 1992, or

PWC SB No. 20962, Revision 4, dated August 10, 1992, at the next engine

shop visit, but not later than December 31, 1995.

(e) For the purpose of this AD, an engine shop visit is defined as

when any major module is separated.

(f) An alternative method of compliance or adjustment of the

compliance time that provides an acceptable level of safety may be used

if approved by the Manager, Engine Certification Office. The request

should be forwarded through an appropriate FAA Principal Maintenance

Inspector, who may add comments and then send it to the Manager, Engine

Certification Office.

NOTE 1: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Engine Certification Office.

NOTE 2: PWC has issued PW100 Service Information Letter (SIL)

No. PW-281 that lists those SB's and revision levels that constitute

acceptable methods of compliance to the requirements of this AD.

(g) Special flight permits may be issued in accordance with 14 CFR

21.197 and 21.199 to operate the aircraft to a location where the

requirements of this AD can be accomplished.

(h) The replacement and modifications shall be done in accordance

with the following service bulletins:

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Document No. Pages Revision Date

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PWC SB No. 1-12 2 December 9, 1991.

21053R2.

Total

pages: 12.

PWC SB No. 1-14 1 May 4, 1992.

21113R1.

Total

pages: 14.

PWC SB No. 1-6 Original February 13, 1992.

21112.

Total

pages: 6.

PWC SB No. 1-13 1 June 22, 1992.

21111R1.

Total

pages: 13.

PWC SB No. 1-18 1 November 12, 1991.

21088R1.

Total

pages: 18.

PWC SB No. 1-18 4 February 1, 1993.

21065R4.

Total

pages: 18.

PWC SB No. 1-11 Original November 8, 1991.

21097.

Total

pages: 11.

PWC SB No. 1-8 5 August 10, 1992.

20957R5.

Total

pages: 8.

PWC SB No. 1-4 4 August 10, 1992.

20962R4.

Total

pages: 4.

PWC SB No. 1-13 3 October 15, 1991.

20914R3.

Total

pages: 13.

PWC SB No. 1-44 Original January 28, 1993.

21211.

Total

pages: 44.

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This incorporation by reference was approved by the Director of the

Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51.

Copies may be obtained from Pratt & Whitney Canada, Technical

Publications Department, 1000 Marie Victorin, Longueuil, Quebec J4G

1A1. Copies may be inspected at the FAA, New England Region, Office of

the Assistant Chief Counsel, 12 New England Executive Park, Burlington,

MA; or at the Office of the Federal Register, 800 North Capitol Street,

NW., suite 700, Washington, DC.

(i) This amendment becomes effective on July 25, 1994.

Issued in Burlington, Massachusetts, on May 26, 1994.

Jay J. Pardee,

Manager, Engine and Propeller Directorate, Aircraft Certification

Service.

[FR Doc. 94-15011 Filed 6-22-94; 8:45 am]

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