AD 98-19-20

This amendment adopts a new airworthiness directive (AD) that is applicable to CFM International CFM56-7B and -7B/2 series turbofan engines. This action requires initial and repetitive inspections of certain hydromechanical unit (HMU) overspeed governor (OSG) spool valves for out-of-specification conditions or the presence of heavy contact or galling on the spool valve, and optional installation of an improved HMU as a terminating action to the inspections. This amendment is prompted by a report of a flameout that occurred on a flight test engine due to a failed HMU OSG spool valve shaft. The actions specified in this AD are intended to prevent failure of the HMU OSG spool valve shaft, and subsequent engine flameout.

Final rule; request for comments.

98-19-20 CFM international: Amendment 39-10761. Docket 98-ANE-55-AD.
Applicability: CFM International CFM56-7B and -7B/2 series turbofan engines, with hydromechanical unit (HMU), Part Number (P/N) 1853M56P04 (AlliedSignal P/N 442008) or 1853M56P05 (AlliedSignal P/N 442026), installed. These engines are installed on but not limited to Boeing 737-600/-700/-800 series aircraft.
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 (d) 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 failure of the HMU overspeed governor (OSG) spool valve shaft, and subsequent engine flameout, accomplish the following:
(a) Inspect HMU, P/N 1853M56P04 (AlliedSignal P/N 442008) and 1853M56P05 (AlliedSignal P/N 442026), in accordance with CFM International Service Bulletin (SB) No. 73-016, Revision 2, dated August 10, 1998, as follows:
(1) For engines with HMUs that have not been previously inspected in accordance with any revision level of CFM International SB No. 73-016, inspect prior to accumulating 300 hours time since new.
(2) For engines with HMUs that have been previously inspected in accordance with any revision level of CFM International SB No. 73-016, inspect within 300 hours time in service (TIS) since the last inspection in accordancewith the SB.
(b) Thereafter, for HMUs that have been inspected in accordance with paragraph (a) of this AD, inspect the HMU at intervals not to exceed 300 hours TIS since the last inspection in accordance with CFM International SB No. 73-016, Revision 2, dated August 10, 1998.
Note 2: The inspections required in paragraphs (a) and (b) of this AD have been published in Chapter 05 of the CFM56-7B series Engine Shop Manual, CFMI-TP.SM.10.
(c) Installation of HMU, P/N 1853M56P06 (AlliedSignal P/N 442098), constitutes terminating action to the inspection requirements of this AD.
(d) 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 requests 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.
(e) 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.
(f) The actions required by this AD shall be done in accordance with the following CFM International SB:

Document No.
Pages
Revision
Date
CFM56-7B SB No. 73-016
1-6
2
August 10, 1998
Total pages: 6.

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 CFM International, Technical Publications Department, 1 Neumann Way, Cincinnati, OH 45215; telephone (513) 552-2981, fax (513) 552-2816. Copies may be inspected at the FAA, New England Region, Officeof 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.
(g) This amendment becomes effective on October 7, 1998.

The Federal Aviation Administration (FAA) has received a report of an engine flameout on a CFM International CFM56-7B series turbofan flight test engine. Due to the similarity of the engines, CFM56-7B/2 series engines could also be affected. Investigation revealed that the flameout occurred as a result of a failed hydromechanical unit (HMU) overspeed governor (OSG) spool valve shaft. The shaft failed as a result of the spinning spool's contact with the valve sleeve inner diameter. Further investigation revealed out-of-specification conditions may exist that can contribute to rotor contact. This condition, if not corrected, could result in a failure of the HMU OSG spool valve shaft, and subsequent engine flameout.
The FAA has reviewed and approved the technical contents of CFM International CFM56-7B Service Bulletin (SB) No. 73-016, Revision 2, dated August 10, 1998, that describes procedures for inspection of HMU OSG spool valves for out-of-specification conditions or the presence of heavy contact or galling on the spool valve.
Since an unsafe condition has been identified that is likely to exist or develop on other engines of the same type design, this AD is being issued to prevent a failure of the HMU OSG spool valve shaft, and subsequent engine flameout. This AD requires initial and repetitive inspections of HMU OSG spool valves for out-of-specification conditions or the presence of heavy contact or galling on the spool valve. The optional installation of an improved HMU, Part Number (P/N) 1853M56P06 (AlliedSignal P/N 442098), constitutes terminating action to the inspection requirements. The actions are required to be accomplished in accordance with the SB described previously.
Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.
Comments Invited
Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.
Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects ofthe rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 98-ANE-55-AD." The postcard will be date stamped and returned to the commenter.
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.
The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, 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. 106(g), 40113, 44701. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: