AD 94-23-09

This amendment supersedes telegraphic airworthiness directive (AD) T89-02-52, which superseded Telegraphic AD T88-22-51 (AD), applicable to Rolls-Royce, plc (R-R) Spey series turbofan engines. Telegraphic AD T88-22-51 reduced cyclic life limits for seventh stage high pressure compressor (HPC) disks from 40,000 total part cycles in service (TPC) to 35,000 TPC for the R-R Spey Model 506-14 and -14D engines. Telegraphic AD T89-02-52 currently requires repetitive inspections or further reduced cyclic life limits for seventh stage HPC disks. This amendment increases the AD's effectivity to include additional R-R Spey engine models, eliminates the option for repetitive inspections, and further reduces the cyclic life limits. This amendment is prompted by further investigation into disk bore cracking that was caused by corrosion. The actions specified by this AD are intended to prevent a seventh stage HPC disk burst due to cracking attributed to corrosion, which may result in an uncontained engine failure.
The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of January 6, 1995.

Final rule.

94-23-09 Rolls-Royce, plc: Amendment 39-9072. Docket 93-ANE-31. Supersedes Telegraphic AD T89-02-52, dated January 26, 1989.
Applicability: Rolls-Royce, plc (R-R) Spey 506-14 series, 511-14 series, and 555-15 series turbofan engines installed on but not limited to British Aerospace BAC 1-11 and Fokker F28 aircraft.
Compliance: Required as indicated, unless accomplished previously.
To prevent a seventh stage high pressure compressor (HPC) disk burst due to cracking attributed to corrosion, which may result in an uncontained engine failure, accomplish the following:
(a) For seventh stage HPC disks that on the effective date of this airworthiness directive (AD) exceed the revised cyclic life limits described in R-R Mandatory Service Bulletin (SB) Sp72- 1034, Revision 1, dated May 4, 1990, remove from service and replace with a serviceable part within 60 days after the effective date of this AD.
(b) For seventh stage HPC disks that on the effective date of this AD do not exceed the revised cyclic life limits described in R-R Mandatory SB Sp72-1034, Revision 1, dated May 4, 1990, remove from service and replace with a serviceable part: either prior to exceeding the revised cyclic life limits, or within 60 days after the effective date of this AD, whichever occurs later.
(c) 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 AD, if any, may be obtained from the Engine Certification Office.
(d) 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) tooperate the aircraft to a location where the requirements of this AD can be accomplished.
(e) The actions required by this AD shall be done in accordance with the following R-R service bulletin:

Document No.
Pages
Revision
Date
Mandatory

SB No. Sp72-1034
1-3
1
May 4, 1990
Total pages: 3.

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 Service Manager, Spey engines, Rolls-Royce, plc, East Kilbride, Glasgow G74 4PY, Scotland. 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.
(f) This amendment becomes effective on January 6, 1995.

The Civil Aviation Authority (CAA), which is the airworthiness authority of the United Kingdom, notified the Federal Aviation Administration (FAA) that an unsafe condition may exist on Rolls-Royce, plc (R-R) Spey series turbofan engines. The CAA advised that they received a report of a three-inch crack extending radially outward from the bore on a seventh stage high pressure compressor (HPC) disk installed in a R-R Spey Model 506-14D engine. The crack originated from a corrosion pit that apparently had been present at the disk's entry into service. Investigation indicated that failure of the engine due to disk burst was imminent. That condition, if not corrected, could result in a seventh stage HPC disk burst due to cracking attributed to corrosion, which may result in an uncontained engine failure.
This engine model is manufactured in the United Kingdom 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, the CAA has kept the FAA informed of the situation described above. The FAA has examined the findings of the CAA, reviewed all available information, and determined that airworthiness directive (AD) action is necessary for products of this type design that are certificated for operation in the United States.
On October 20, 1988, the FAA issued Telegraphic AD T88-22-51, which reduced cyclic life limits for seventh stage HPC disks from 40,000 total part cycles in service (TPC) to 35,000 TPC for the R-R Spey Model 506-14 and -14D engines. On January 26, 1989, the FAA issued Telegraphic AD T89-02-52, which supersedes Telegraphic AD T88-22-51, and currently requires repetitive inspections or further reduced cyclic life limits for seventh stage HPC disks.
A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding Telegraphic AD T89-02-52 was published in the Federal Register on January 11, 1994 (59 FR 1500). That action proposed to increase the AD's effectivity to include additional R-R Spey engine models, eliminate the option for repetitive inspections of seventh stage HPC disks, further reduce the cyclic life limits, and require removing from service disks that exceed the revised cyclic life limits following the schedule established in this AD.
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comment received.
The commenter concurs with the rule as proposed.
After careful review of the available data, including the comment noted above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed.
The FAA estimates that 173 engines installed on aircraft of U.S. registry will be affected by this AD, and that it will not take any additional work hours per engine to accomplish the required actions. Replacement parts, prorated for the reduced life, will cost approximately $1,718 per engine. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $297,214.
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. 39.13 - [AMENDED]
2. Section 39.13 is amended by adding the following new airworthiness directive: