AD 94-25-09

This amendment adopts a new airworthiness directive (AD), applicable to Rolls-Royce, plc Spey series turbofan engines, that requires a one-time inspection of stage 1 and stage 2 high pressure turbine (HPT) and low pressure turbine (LPT) disks for cracks and corrosion pitting. This amendment is prompted by a report of a stage 7 high pressure compressor disk found cracked due to corrosion. The actions specified by this AD are intended to prevent an HPT or LPT 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 February 17, 1995.

Final rule.

94-25-09 Rolls-Royce, plc: Amendment 39-9093. Docket 93-ANE-43.
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 series and Fokker F28 series aircraft.
Compliance: Required as indicated, unless accomplished previously.
To prevent a high pressure turbine (HPT) or low pressure turbine (LPT) disk burst due to cracking attributed to corrosion, which may result in an uncontained engine failure, accomplish the following:
(a) Perform a one-time inspection for cracks and corrosion pitting in stage 1 and stage 2 HPT disks that on the effective date of this airworthiness directive (AD) have completed 40% or more of their published Group "A" lives, in accordance with the procedures and schedule described in R-R Service Bulletin (SB) No. Sp72-1044, dated September 1992, at the next shop visit after the effective date of this AD.
(b) Perform a one-time inspection for cracks and corrosion pitting in stage 1 and stage 2 HPT disks that on the effective date of this AD have completed less than 40% of their published Group "A" lives, in accordance with the procedures and schedule described in R-R SB No. Sp72- 1044, dated September 1992, at the first shop visit after completing 40% of their published Group "A" lives.
(c) Perform a one-time inspection for cracks and corrosion pitting in stage 1 and stage 2 LPT disks that on the effective date of this AD have completed 40% or more of their published Group "A" lives, in accordance with the procedures and schedule described in R-R SB No. Sp72- 1044, dated September 1992, at the next shop visit after the effective date of this AD.
(d) Perform a one-time inspection for cracks and corrosion pitting in stage 1 and stage 2 LPT disks that on the effective date of this AD have completed less than 40% of their published Group "A" lives, in accordance with the procedures and schedule described in R-R SB No. Sp72- 1044, dated September 1992, at the first shop visit after completing 40% of their published Group "A" lives.
(e) Replace with a serviceable part, disks that do not meet the inspection requirements described in section 72-50 of the applicable R-R Spey Engine Overhaul Manual, prior to return to service.
(f) Mark disks that meet the inspection requirements described in section 72-50 of the applicable R-R Spey Engine Overhaul Manual in accordance with R-R SB No. Sp72-1044, dated September 1992, prior to return to service.
(g) For the purpose of this AD, a shop visit is defined as an engine removal where engine maintenance entails removal of either HPT or LPT disks.
(h) 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.
(i) 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.
(j) The inspection, and replacement, if necessary, of the disks, shall be done in accordance with the following service bulletin:

Document No.
Pages
Date
R-R SB No. Sp72-1044
1-2
September 1992
Total Pages: 2.

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 beinspected 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.
(k) This amendment becomes effective on February 17, 1995.

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) Spey series turbofan engines was published in the Federal Register on January 11, 1994 (59 FR 1500). That action proposed to require a one-time inspection of stage 1 and stage 2 high pressure turbine (HPT) and low pressure turbine (LPT) disks for cracks and corrosion pitting once the disks have completed at least 40% of their published Group "A" cyclic life limits as specified in the applicable overhaul manual. These disks must be inspected in accordance with the applicable overhaul manual during the engine's next shop visit where either the HPT or LPT disks are removed after the effective date of this AD. Accomplishment of this inspection will allow stage 1 and stage 2 HPT and LPT disks to complete the remainder of their current published cyclic life limits. The actions would be required to be accomplished in accordance with R-R Service Bulletin No. Sp72- 1044, dated September 1992.
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the one comment received.
The commenter concurs with the AD as proposed.
In addition, the definition of shop visit has been clarified to eliminate the reference to next scheduled disk inspection and include next disk removal.
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 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.
The FAA estimates that 173 engines installed on aircraft of U.S. registry will be affected by this AD and that the average labor rate is $55 per work hour. The FAA estimates that it will take no additional work hours per engine to accomplish the required actions to the HPT's as the inspection is performed during regular turbine overhauls. Approximately 80% of the engines will require an additional 25 work hours of extra access, inspection, and rebuild time to perform the required LPT inspection. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $189,750.
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), 1421and 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: