Airworthiness directives: Royce plc,
[Federal Register: November 17, 1999 (Volume 64, Number 221)]
[Rules and Regulations]
[Page 62570-62572]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr17no99-4]
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.
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
-
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 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. 99-29825Filed11-16-99; 8:45 am]
BILLING CODE 4910-13-P
