Airworthiness Directives; Rolls-Royce plc Tay 620-15, Tay 650-15, and Tay 651-54 Series Turbofan Engines

[Federal Register Volume 64, Number 221 (Wednesday, November 17, 1999)]
[Rules and Regulations]
[Pages 62570-62572]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-29825]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NE-26-AD; Amendment 39-11423; AD 99-24-01]
RIN 2120-AA64


Airworthiness Directives; Rolls-Royce plc Tay 620-15, Tay 650-15, 
and Tay 651-54 Series Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to Rolls-Royce plc Tay 620-15, Tay 650-15, and Tay 651-54 
series turbofan engines, that requires initial and repetitive visual 
inspections of the emergency fuel shutoff cable for broken strands or 
failed cables, and, if necessary, replacement with serviceable parts. 
This amendment is prompted by reports of broken strands and failed 
emergency fuel shutoff cables. The actions specified by this AD are 
intended to prevent emergency fuel shutoff cable failure, which could 
result in the non-operation of the emergency fuel shut-off system in 
the event of a low pressure shaft failure.

DATES: Effective January 18, 2000.

ADDRESSES: The service information referenced in this AD may be 
obtained from Rolls-Royce plc, Technical Publications Department, PO 
Box 31, Derby DE24 8BJ England; telephone +44 1332 242424, fax +44 1332 
37645. This information may be examined at the Federal Aviation 
Administration (FAA), New England Region, Office of the Regional 
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: James Lawrence, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (781) 
238-7176, fax (781) 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 Rolls-Royce plc (R-R) Tay 620-15, 
Tay 650-15, and Tay 651-54 series turbofan engines was published in the 
Federal Register on June 23, 1999 (64 FR 33435). That action proposed 
to require initial and repetitive visual inspections of the emergency 
fuel shutoff cable for broken strands or failed cables, and, if 
necessary, replacement with serviceable parts. That action was prompted 
by reports of broken strands and failed emergency fuel shutoff cables. 
That condition, if not corrected, could result in the non-operation of 
the emergency fuel shutoff system in the event of a low pressure shaft 
failure.

Comments Received

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Excessive Time for Initial Inspection

    One commenter states the proposed compliance time of 1,000 hours 
time in service (TIS) after the effective date of this AD for the 
initial inspection is excessive. Considering the time needed to process 
rulemaking, the commenter believes the compliance time to be excessive 
and drawn out for the initial inspection considering the potential 
hazards if emergency fuel shut-off control is lost. The commenter 
believes that non-operation of this component could result in the 
initiation of or the continued feeding of a fire.
    The Federal Aviation Administration (FAA) does not concur. The 
emergency fuel shutoff system is designed to protect the aircraft in 
the event of a low pressure shaft failure. It has no other function. 
The failure detection elements are a simple linkage actuated by 
relative rotational movement between the engine center oil tube that is 
splined to the fan disc, and the rear of the low pressure turbine 
shaft. Effectively, it is monitoring the angular positions of the fan 
disc relative to the rear of the low pressure turbine. A failure of the 
low pressure shaft is therefore the only way in which the system can be 
activated. The emergency fuel shutoff system is not designed as a 
mechanism to control fire and is not activated in the event of a fire. 
The FAA has determined that the inspection intervals specified have 
been established in accordance with extensive service investigation and 
are appropriate.

Inspection Intervals Do Not Match Maintenance Checks

    One commenter states that the initial and repetitive inspection 
interval of 1,000 hours TIS does not match any of the commenter's 
maintenance check intervals. The commenter would like to do the 
inspection at every one-half C-check interval or 2600 hours. Then if 
cable replacement is necessary, experienced mechanics and equipment

[[Page 62571]]

would be available to replace the cable. The commenter justifies the 
change request based upon the excellent reliability of the Tay series 
engine turbine. The engine series has never seen a fuel shutoff cable 
activation event. The commenter recommends that the FAA consider the 
engine reliability in the final rule and make the interval consistent 
with the regular C-check intervals.
    The FAA does not concur. The 1,000 hours TIS inspection is based on 
service experience. Service experience has shown that cable strands 
fail on average of one per 890 hours and that a number of external 
strands will wear concurrently such that further strand failures occur 
relatively quickly following the first strand failure. The UK CAA has 
informed the FAA that adopting the requested 2,600 hour inspection 
cycle could result in as many as 9 broken cable strands. This could 
render the emergency fuel shutoff control ineffective. The sole purpose 
of the emergency fuel shutoff control is to guard against a turbine 
overspeed condition in the event of low pressure shaft shear.

Conclusion

    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 as proposed.

Economic Analysis

    There are approximately 900 engines of the affected design in the 
worldwide fleet. The FAA estimates that 451 engines installed on 
aircraft of U.S. registry will be affected by this AD, that it will 
take approximately 0.25 work hours to accomplish the inspections, 3 to 
28 work hours per engine to remove and replace an unacceptable 
emergency fuel shutoff cable, depending on engine aircraft installation 
and position, and that the average labor rate is $60 per work hour. 
Required parts cost approximately $86 per engine. The total cost for 
inspections is estimated to be $6,750. The total cost for replacing 
parts on the Fokker F70 and Fokker F100 aircraft is estimated to be 
$75,125. The total cost for replacing parts on the No. 1 position 
engine on Boeing 727 aircraft is estimated to be $14,918. The total 
cost for replacing parts on the No. 2 and 3 position engines on Boeing 
727 aircraft, since engine removal is required for these two engine 
positions, is $197,837. Based on these figures, the total cost impact 
of the on U.S. operators is estimated to be $294,630.

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 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, 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.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

99-24-01  Rolls-Royce plc: Amendment 39-11423. Docket 99-NE-26-AD.

    Applicability: Rolls-Royce plc (R-R) Tay 620-15, Tay 650-15, and 
Tay 651-54 series turbofan engines, installed on but not limited to 
Fokker F.28 Mark 0070 series, Fokker F.28 Mark 0100 series, and 
Boeing 727 series aircraft modified with STC SA8472SW.

    Note 1: This airworthiness directive (AD) applies to each engine 
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 engines 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 (b) 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 as indicated, unless accomplished 
previously.
    To prevent emergency fuel shutoff cable failure, which could 
result in the non-operation of the emergency fuel shut-off system in 
the event of a low pressure shaft failure, accomplish the following:

Inspections

    (a) Perform initial and repetitive visual inspections of the 
emergency fuel shutoff cable for broken strands or failed cables as 
follows:
    (1) Initially inspect the emergency fuel shutoff cable within 
1,000 hours time-in-service (TIS) after the effective date of this 
AD.
    (i) If the emergency fuel shutoff cable has no strands broken, 
re-inspect within 1000 hours TIS after the inspection.
    (ii) If the emergency fuel shutoff cable has 1, 2, or 3 strands 
broken, re-inspect within 800 hours TIS after the inspection.
    (iii) If the emergency fuel shutoff cable has 4, 5, or 6 strands 
broken, replace the cable within 100 hours TIS after the inspection.
    (iv) If the emergency fuel shutoff cable has 7 or more strands 
broken, or the cable has failed, replace the cable within 25 hours 
TIS after the inspection.
    (2) Thereafter, perform inspections of the emergency fuel 
shutoff cable and replace the emergency fuel shutoff cable as 
provided in paragraph (a)(1) of this AD.

    Note 2: Information on inspection of the emergency fuel shutoff 
cable and replacement of cables may be found in R-R Service Bulletin 
(SB) No. Tay 76-1434, Revision 1, dated August 28, 1998, and 
Maintenance Manual 76-23-00.

Alternative Methods of Compliance

    (b) 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. 
Operators shall submit their request through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, Engine Certification Office.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the Engine Certification Office.

Ferry Flights

    (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 aircraft to a location where 
the requirements of this AD can be accomplished.
    (d) This amendment becomes effective on January 18, 2000.


[[Page 62572]]


    Issued in Burlington, Massachusetts, on November 9, 1999.
David A. Downey,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 99-29825 Filed 11-16-99; 8:45 am]
BILLING CODE 4910-13-P

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