AD 98-07-02

This amendment adopts a new airworthiness directive (AD) that is applicable to CFM International CFM56-2, -3, -3B, and -3C series turbofan engines. This action requires the removal from service of certain No. 3 bearing rear stationary air/oil seals, replacement with serviceable parts, and the installation of retention bushings. This action also requires the removal from service of high pressure compressor rotor (HPCR) stage 1-2 spools that have contacted the outer cone of the seal. This amendment is prompted by several reports of outer cone separation of the No. 3 bearing rear stationary air/oil seal. The actions specified in this AD are intended to prevent rubs between the outer cone of the No. 3 bearing rear stationary air/oil seal and the HPCR stage 1-2 spool, which could result in a potential uncontained failure of the HPCR stage 1-2 spool, and damage to the aircraft.

Final rule; request for comments.

98-07-02 CFM International: Amendment 39-10420. Docket 98-ANE-16-AD.
Applicability: CFM International CFM56-2, -3, -3B, and -3C series turbofan engines installed on, but not limited to, McDonnell Douglas DC-8 series and Boeing 737 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 (e) 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 rubs between the outer cone of the No. 3 bearing rear stationary air/oil seal and the high pressure compressor rotor (HPCR) stage 1-2 spool, which could result in a potential uncontained failure of the HPCR stage 1-2 spool, and damage to the aircraft, accomplish the following:
(a) For CFM International CFM56-2 series engines, with high pressure compressor rotor (HPCR) stage 1-2 spool, Part Number (P/N) 9992M60G07, with part Serial Number (S/N) listed in CFM56-2 Service Bulletin (SB) No. 72-825, dated January 23, 1998, installed, accomplish the following:
(1) Remove the HPCR stage 1-2 spool from service at the next engine shop visit after the effective date of this AD, or prior to accumulating 2,000 cycles in service (CIS) since the engine shop visit that first confirmed the rub event, whichever occurs first, in accordance with CFM International CFM56-2 SB No. 72-825, dated January23, 1998, and replace with a serviceable HPCR stage 1-2 spool.
(2) Install No. 3 bearing rear air/oil seal retention bushings in accordance with CFM International CFM56-2 SB No. 72-823, dated August 12, 1997.
(b) For CFM International CFM56-3, -3B, and -3C series engines, with HPCR stage 1-2 spool, P/N 1589M66G02, with part S/Ns listed in CFM International CFM56-3/-3B/-3C SB No. 72-856, dated January 23, 1998, installed, accomplish the following:
(1) Remove the HPCR stage 1-2 spool from service at the next engine shop visit after the effective date of this AD, or prior to accumulating 2,000 CIS since the engine shop visit that first confirmed the rub event, whichever occurs first, in accordance with CFM56-3/-3B/-3C SB No. 72-856, dated January 23, 1998, and replace with a serviceable HPCR stage 1-2 spool.
(2) Install No. 3 bearing rear air/oil seal retention bushings in accordance with CFM International CFM56-3/-3B/-3C SB No. 72-855, Revision 1, dated February 9, 1998.(c) For CFM56-3, -3B, and -3C engines, having any of the following engine S/Ns: 856692, 856709, 856713, 856799, 856673, 856691, 856694, 856696, 856697, 856746, 856780, 857669, 857685, 857686, 857704, and 859115; accomplish the following within 15 days after the effective date of this AD:
(1) Remove from service No. 3 bearing rear stationary air/oil seal, P/N 1663M91G03, and replace with a serviceable No. 3 bearing rear stationary air/oil seal. No. 3 bearing rear stationary air/oil seals removed in accordance with this paragraph are unserviceable.
(2) Install No. 3 bearing rear air/oil seal retention bushings in accordance with CFM International CFM56-3/-3B/-3C SB No. 72-855, Revision 1, dated February 9, 1998.
(d) For the purpose of this AD, the following definitions apply:
(1) A shop visit is defined as the induction of an engine into the shop for any maintenance.
(2) A serviceable HPCR stage 1-2 spool is defined as a spool without a rub or scratch indication.(3) A serviceable No. 3 bearing rear stationary air/oil seal is defined as a new seal, P/N 1663M91G03, that is not identified by S/N in Table 1 of this AD.

Table 1 No. 3 Bearing Rear Stationary Air/Oil Seal S/Ns P/N 1663M91G03

CTD81631
CTD81907
CTD81908
CTD81998
CTD82004
CTD82132
CTD82208
CTD82210
CTD82212
CTD82213
CTD82271
CTD82295
CTD82297
CTD82298
CTD82300
CTD82304
CTD82457
CTD82759
CTD82766
CTD82767
CTD82788
CTD82817
CTD82822
CTD82854
CTD82855
CTD82856
CTD82857
CTD82859
CTD82962
CTD83232
CTD83474
CTD83837
CTD83839
CTD84100
CTD84138
CTD84140
CTD84141
CTD84143
CTD84144
CTD84145
CTD84148
CTD84203
CTD84206
CTD84207
CTD84258
CTD84262
CTD84360
CTD84363
CTD84604
CTD84712
CTD84741
CTD85147
CTD85148
CTD85149
CTD85161
CTD85162
CTD85166
CTD85168
CTD85169
CTD85170
CTD85172
CTD85348
CTD85349
CTD85351
CTD85352
CTD85353
CTD85354
CTD85355
(e) 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 2: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Engine Certification Office.
(f) 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.
(g) The actions required by this AD shall be done in accordance with the following CFM International SBs:

Document No.
Pages
Revision
Date
CFM56-2 SB No. 72-823
1-12
Original
August 12, 1997
Total pages: 12.

CFM56-2 SB No. 72-8251-7
Original
January 23, 1998
Total pages: 7.

CFM56-3/-3B/-3C, SB No. 72-856
1-8
Original
January 23, 1998
Total pages: 8.

CFM56-3/-3B/-3C, SB No. 72-855
1-16
1
February 9, 1998
Total pages: 16.

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, Office of 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.
(h) This amendment becomes effective on March 30, 1998.

The Federal Aviation Administration (FAA) has received 26 reports where the inner and outer cones of the No. 3 bearing rear stationary air/oil seal have separated on CFM International CFM56-2, -3, -3B, and -3C series turbofan engines. The seal consists of two composite cones which are bonded together with an adhesive. Investigation revealed that the adhesive used on certain seals have less bonding capability than required. When the seal debonds, the outer cone moves aft and allows oil to migrate into the high pressure compressor rotor (HPCR) flowpath, which may result in oil fumes in the cabin. As the seal continues to move aft, the outer cone contacts the bore of the stage 1 disk of the HPCR stage 1-2 spool. New retention bushings exist, that when installed, will preclude a separated seal from contacting the HPCR stage 1-2 spool. This condition, if not corrected, could result in rubs between the outer cone of the No. 3 bearing rear stationary air/oilseal and the HPCR stage 1-2 spool, which could result in a potential uncontained failure of the HPCR stage 1-2 spool, and damage to the aircraft.
The FAA has reviewed and approved the technical contents of CFM International CFM56-2 Service Bulletin (SB) No. 72-825 and CFM56-3/-3B/-3C SB No. 72-856, both dated January 23, 1998, that describes procedures for removal from service of certain HPCR stage 1-2 spools from engines that have documented rubs on the stage 1 disk bore due to contact with the outer cone of the No. 3 bearing rear stationary air/oil seal. In addition, the FAA has reviewed and approved the technical contents of CFM International CFM56-2 SB No. 72-823, dated August 12, 1997, and CFM56-3/-3B/-3C SB No. 72-855, Revision 1, dated February 9, 1998, that describes procedures for installation of the No. 3 bearing rear stationary air/oil seal retention bushings.
Since an unsafe condition has been identified that is likely to exist or develop on other engines of the sametype design, this AD is being issued to prevent rubs between the outer cone of the No. 3 bearing rear stationary air/oil seal and the HPCR stage 1-2 spool, which could result in a potential uncontained failure of the HPCR stage 1-2 spool. This AD requires the removal from service, within 15 days after the effective date of this AD, of certain No. 3 bearing rear stationary air/oil seals, replacement with serviceable parts, and the installation of retention bushings. This AD also requires the removal from service of HPCR stage 1-2 spools that have contacted the outer cone of the seal at the next engine shop visit after the effective date of this AD, or prior to accumulating 2,000 cycles in service (CIS) since the engine shop visit that first confirmed the rub event. The 2,000 CIS interval was established based on an extensive test program on the CFM56-5 series engine. The compliance end-date was determined based upon risk assessment and parts availability. The actions are requiredto be accomplished in accordance with the SBs 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. Factualinformation 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 of the 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-16-AD." The postcard will be date stamped and returned to the commenter.
The regulations adopted herein will nothave 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. Acopy 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: