Airworthiness Directives; Pratt & Whitney JT8D Series Turbofan Engines

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 91-ANE-39; Amendment 39-9065; AD 94-23-03]

Airworthiness Directives; Pratt & Whitney JT8D Series Turbofan

Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: This amendment adopts a new airworthiness directive (AD),

applicable to Pratt & Whitney (PW) JT8D series turbofan engines, that

requires installation and periodic inspection of temperature indicators

installed on the No. 4 and 5 bearing compartment scavenge oil tube and

performance of any necessary corrective action. This amendment is

prompted by reports of high pressure turbine (HPT) shaft fractures

caused by oil fires that resulted from internal leakage of thirteenth

stage compressor discharge air into the No. 4 and 5 bearing

compartment. The actions specified by this AD are intended to prevent

fracture of the HPT shaft, which can result in uncontained release of

engine fragments, engine fire, inflight engine shutdown, or possible

aircraft damage.

DATES: Effective January 31, 1995.

The incorporation by reference of certain publications listed in

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

of January 31, 1995.

ADDRESSES: The service information referenced in this AD may be

obtained from Pratt & Whitney, Technical Publications Department, M/S

132-30, 400 Main Street, East Hartford, CT 06108. 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; or at the Office of the Federal Register, 800

North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Mark A. Rumizen, Aerospace Engineer,

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

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

238-7137, fax (617) 238-7199.

SUPPLEMENTARY INFORMATION: 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 Pratt & Whitney (PW) JT8D series

turbofan engines, was published as a notice of proposed rulemaking

(NPRM) in the Federal Register on January 24, 1992 (57 FR 2857). That

action proposed to require the installation and periodic inspection of

temperature indicators (temp tabs) installed on the No. 4 and 5 bearing

compartment scavenge oil tube, performance of any necessary corrective

action, and to require the installation of No. 4 and 5 bearing

compartment hardware modifications for certain engines.

On July 19, 1993, the FAA issued a Supplemental NPRM (58 FR 40083,

July 27, 1993) that reopened the comment period, due to comments

received and the determination that the bearing compartment hardware

modifications do not adequately prevent internal leakage of thirteenth

stage compressor discharge air into the No. 4 and 5 bearing

compartment. That Supplemental NPRM proposed to require installation of

improved temperature indicators to extend the compliance time for

installation of temperature indicators, and to eliminate the

requirement to perform No. 4 and 5 bearing compartment hardware

modifications, in accordance with PW Alert Service Bulletin (ASB) No.

5944, Revision 2, dated June 8, 1992, and ASB No. 6053, Revision 7,

dated May 24, 1993.

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 states that PW JT8D-Std series turbofan engines

installed in Boeing 727 series aircraft should be exempt from the

requirements of the AD based on the absence of uncontained engine

failures over the last 16 years for those engines. The FAA concurs. The

FAA has determined that the risk of uncontained engine failures on PW

JT8D-Std series turbofan engines installed in Boeing 727 series

aircraft has been reducing as newer model engines with improved

containment capability have been accumulating an increasing percentage

of fleet operating hours. Based on this determination, the FAA has

concluded that a mandatory requirement to install the temperature

indicators on these engines cannot be justified. Therefore, this final

rule has been revised to remove from the applicability PW JT8D-Std

series engines.

One commenter states that the repetitive inspections and associated

record keeping should be incorporated into the operators' FAA-approved

maintenance program. The FAA does not concur. The FAA has determined

that it is necessary to keep the repetitive inspections under the AD

and separate from the routine-approved maintenance program to

distinguish this activity as being critical to flight safety. In

addition, this AD represents an interim program until installation of

the HPT containment hardware in PW JT8D-200 series turbofan engines has

been accomplished in accordance with AD 93-23-10.

Two commenters state that the temp tab installation requirement

should be extended beyond the current 90 days. The FAA does not concur.

The FAA has provided ample notice of this requirement and extension of

the installation grace period will increase the probability of a No. 4

and 5 bearing compartment fire and possible shaft fracture. In

addition, this 90 day grace period represents an increase from 65 days

proposed in the NPRM.

Two commenters state that the repetitive inspection interval should

be changed from 65 hours time in service (TIS) to a longer interval or

an interval based on calendar time. The FAA does not concur. Extension

of this interval will increase the probability of a No. 4 and 5

compartment fire to an unacceptable level. This interval represents a

maximum limit, and shorter intervals can be selected to be consistent

with calendar time maintenance schedules.

One commenter states that temp tabs are unreliable and are subject

to oil contamination and false indications, and that the program should

be delayed until a new indicating method is developed. The FAA does not

concur. The temp tab configuration specified in this rule and

associated PW SB represent an improved version that incorporates a

sealant which is applied over the indicator and prevents oil

saturation. In addition, a procedure to determine if oil saturation has

occurred is included in the associated PW SB. PW has developed a more

costly mechanical pop-up indicator that is resistant to oil

contamination. Introduction of this indicator is currently under

evaluation and it may be available as an alternate means of compliance

at a future date.

Two commenters state that the cost impact does not take into

account the expense of maintaining the temp tab indicators and the

costs of troubleshooting false indications, and that, therefore, the

total cost estimate for compliance with the AD should be increased to

reflect these indirect costs. The FAA does not concur. The economic

analysis reflects the direct cost of compliance with the requirements

of the AD actions that the FAA has determined are necessary to correct

an unsafe condition likely to exist on engines of this type design. The

FAA has determined that adherence to the temp tab indicator

installation instructions provided in PW SB No. 5944 will allow for

reliable installation of the indicators. Once installed correctly, the

temp tab indicators will provide warning of potentially catastrophic

and costly abnormal engine conditions.

One commenter states that the temp tab indicator part numbers

should not be stated in the AD. The commenter maintains that the AD

would then still be applicable for improved indicators with new part

numbers when they are introduced. The FAA does not concur. A new

revision to PW SB No. 5944 would be required to introduce new part

numbers for new temp tab indicators, and the FAA may approve the new

revision and installation of these new temp tab indicators as an

alternative method of compliance.

One commenter states that utilizing oil system condition monitoring

and checks should allow for an increased temp tab indicator inspection

interval. The FAA does not concur. The FAA has determined that the temp

tab indicators are the most effective indicator of No. 4 and 5 bearing

compartment overtemperature conditions. However, other oil system

checks, such as oil consumption monitoring, breather pressure, and oil

pressure, can be used to assist in the troubleshooting process and help

identify bearing compartment overtemperature conditions.

One commenter agrees with the rule as proposed.

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 increase the scope of

the AD.

There are approximately 2,432 PW JT8D-200 series engines of the

affected design in the worldwide fleet. The FAA estimates that 1,044

engines installed on aircraft of U.S. registry will be affected by this

AD, that it will take approximately 1.5 work hours per engine to

accomplish the required actions, and that the average labor rate is $55

per work hour. Based on these figures, the total cost impact of the AD

on U.S. operators is estimated to be $85,883.

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. 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 adding the following new

airworthiness directive:

94-23-03 Pratt & Whitney: Amendment 39-9065. Docket 91-ANE-39.

Applicability: Pratt & Whitney (PW) JT8D-209, -217, -217A, -

217C, and -219 turbofan engines that have not installed high

pressure turbine (HPT) containment hardware in accordance with AD

93-23-10. These engines are installed on but not limited to

McDonnell Douglas MD-80 series and Boeing 727 series aircraft.

Compliance: Required as indicated, unless accomplished

previously.

To prevent fracture of the HPT shaft, which can result in

uncontained release of engine fragments, engine fire, inflight

engine shutdown, or possible aircraft damage, accomplish the

following:

(a) Install and inspect one or two temperature indicators, part

number (P/N) 810486, or a single or double set of P/N 809129 and P/N

809130 temperature indicators, on the No. 4 and 5 bearing

compartment scavenge oil tube, as follows:

(1) Install temperature indicators on the No. 4 and 5 bearing

compartment scavenge oil tube in accordance with Section 2.A.(1) of

the Accomplishment Instructions of PW Alert Service Bulletin (ASB)

No. 5944, Revision 2, dated June 8, 1992, within 90 days after the

effective date of this airworthiness directive (AD).

(2) Visually inspect temperature indicators within 65 hours TIS

of installation. Thereafter, inspect at intervals not to exceed 65

hours TIS since last inspection.

(3) If upon inspection, the color of any temperature indicator

window(s) has turned completely black, perform troubleshooting and

diagnostic testing and corrective action as required, in accordance

with Section 2.A.(2)(c) and (d) or (f) and (g), as applicable, of

the Accomplishment Instructions of PW ASB No. 5944, Revision 2,

dated June 8, 1992. Prior to returning the engine to service,

replace any temperature indicator that has turned black and inspect

in accordance with paragraph (a)(2) and (a)(3) of this AD.

(b) For aircraft installations utilizing one P/N 810486

indicator or one set of P/N 809129 and 809130 indicators, and

inspection reveals a missing indicator, inspect the remaining

temperature indicator, if applicable, to determine if the indicator

window has turned completely black. If the indicator window has

turned completely black, perform troubleshooting and diagnostic

testing, and corrective action as required, in accordance with

paragraph (a)(3) of this AD. If the indicator window has not turned

completely black or if there are no additional indicators installed,

then install a new indicator in accordance with Section 2.A.(1) of

the Accomplishment Instruction of PW ASB No. 5944, Revision No. 2,

dated June 8, 1992, prior to return to service, and visually inspect

the temperature indicator within 65 hours TIS since installation.

Thereafter, inspect at intervals not to exceed 65 hours TIS since

last inspection in accordance with paragraphs (a)(2) and (a)(3) of

this AD.

(c) For aircraft installations utilizing two P/N 810486

indicators or two sets of P/N 809129 and 809130 indicators, and

inspection reveals a missing indicator(s), inspect the remaining

temperature indicator(s), if applicable, to determine if the

indicator window has turned completely black. If the indicator

window has turned completely black, perform troubleshooting and

diagnostic testing, and corrective action as required, in accordance

with paragraph (a)(3) of this AD. If the indicator window has not

turned completely black, install a new indicator(s) in accordance

with Section 2.A.(1) of the Accomplishment Instructions of PW ASB

No. 5944, Revision 2, dated June 8, 1992, prior to return to

service, and visually inspect the temperature indicator within 65

hours TIS since installation. Thereafter, inspect at intervals not

to exceed 65 hours TIS since last inspection in accordance with

paragraphs (a)(2) and (a)(3) of this AD.

(d) Report the data elements identified in Appendix E of the

Accomplishment Instructions of PW ASB No. 5944, Revision 2, dated

June 8, 1992, whenever an overtemperature condition is observed on

any color temperature indicator which is the result of an internal

engine problem only and not resulting from an external cause

corrected by the published troubleshooting procedures. Data elements

should be reported within 30 days of determining that the

overtemperature condition is the result of an internal engine

problem, to the Manager, Engine Certification Office, Engine and

Propeller Directorate, Aircraft Certification Service, FAA, 12 New

England Executive Park, Burlington, MA 01803-05299; fax (617) 238-

7199. The reporting requirements of this AD terminate six months

from the effective date of the AD.

(e) Information collection requirements contained in this

regulation have been approved by the Office of Management and Budget

under the provisions of the Paperwork Reduction Act of 1980 (Pub. L.

96-511) and have been assigned OMB control number 2120-0056.

(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: Information concerning the existence of approved

alternative methods of compliance with this airworthiness directive,

if any, may be obtained from the Engine Certification Office.

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

Secs. 21.197 and 21.199 of the Federal Aviation Regulations (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 installations and inspections shall be done in

accordance with the following service bulletin:

------------------------------------------------------------------------

Document No. Pages Revision Date

------------------------------------------------------------------------

PW ASB No. 5944............. 1-44 2 June 8, 1992.

Total pages: 44

------------------------------------------------------------------------

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, Technical

Publications Department, M/S 132-30, 400 Main Street, East Hartford,

CT 06108. 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 January 31, 1995. Issued

in Burlington, Massachusetts, on November 3, 1994.

Jay J. Pardee,

Manager, Engine and Propeller Directorate, Aircraft Certification

Service.

[FR Doc. 94-28374 Filed 12-1-94; 8:45 am]

BILLING CODE 4910-13-P