[Federal Register Volume 64, Number 238 (Monday, December 13, 1999)]
[Proposed Rules]
[Pages 69428-69430]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-32194]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NE-57-AD]
RIN 2120-AA64


Airworthiness Directives; CFM International CFM56-2, -2A, 2B, -3, 
-3B, and -3C Series Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to CFM International CFM56-2, -2A, -
2B, -3, -3B, and -3C series turbofan engines. This proposal would 
require a one-time eddy current inspection (ECI) for cracks in the bolt 
holes of high pressure turbine (HPT) front rotating air seals. This 
proposal is prompted by reports of machining anomalies in a bolt hole 
that led to an HPT front rotating air seal failure. The actions 
specified by the proposed AD are intended to detect cracks in the bolt 
holes of HPT front rotating air seals, which can lead to an uncontained 
engine failure and damage to the aircraft.

DATES: Comments must be received by January 12, 2000.

ADDRESSES: Submit comments to the Federal Aviation Administration 
(FAA), New England Region, Office of the Regional Counsel, Attention: 
Rules Docket No. 99-NE-57-AD, 12 New England Executive Park, 
Burlington, MA 01803-5299. Comments may also be sent via the Internet 
using the following address: ``[email protected]''. Comments sent 
via the Internet must contain the docket number in the subject line. 
Comments may be inspected at this location between 8:00 a.m. and 4:30 
p.m., Monday through Friday, except Federal holidays.
    The service information referenced in the proposed rule may be 
obtained from CFM International, Technical Publications Department, 1 
Neumann Way, Cincinnati, OH 45215; telephone (513) 552-2800, fax (513) 
552-2816. This information may be examined at the FAA, New England 
Region, Office of the Regional Counsel, 12 New England Executive Park, 
Burlington, MA.

FOR FURTHER INFORMATION CONTACT: James Rosa, Aerospace Engineer, Engine 
Certification Office, FAA, Engine and Propeller Directorate, 12 New 
England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-
7152, fax (781) 238-7199.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications should identify the Rules Docket number 
and be submitted to the address specified above. All communications 
received on or before the closing date for comments, specified above, 
will be considered before taking action on the proposed rule. The 
proposals contained in this notice may be changed in light of the 
comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with 
the substance of this proposal 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 99NE-57-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, New England Region, Office of the Regional Counsel, 
Attention: Rules Docket No. 99-NE-57-AD, 12 New England Executive Park, 
Burlington, MA 01803-5299.

Discussion

    The Federal Aviation Administration (FAA) has received a report of 
an uncontained engine failure on a CFM International Model CFM56-3 
turbofan engine. An investigation revealed a crack in a bolt hole of 
the high pressure turbine (HPT) front rotating air seal due to 
machining anomalies. The manufacturer has identified other HPT front 
rotating air seals by serial number (S/N) that may have the same 
anomalies. This condition, if not corrected, could result in cracks in 
the bolt holes of HPT front rotating air seals, which can lead to an 
uncontained engine failure and damage to the aircraft.

Service Information

    The FAA has reviewed and approved the technical contents of the 
following CFM International Service Bulletins (SBs): CFM56-2 SB 72-869, 
dated November 12, 1999; CFM56-2A SB 72-470, dated November 12, 1999, 
CFM56-2B SB 72-611, dated November 12, 1999, and CFM56-3/3B/3C SB 72-
922, dated November 12, 1999. These SBs describe the procedures for 
eddy current inspections (ECI) for cracks in the bolt holes of HPT 
front rotating air seals caused by machining anomalies. Additionally, 
these SBs identify by S/N the HPT front rotating air seals that may 
have the same anomalies.

[[Page 69429]]

Proposed Actions

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would require a one-time ECI for cracks in the bolt holes 
of HPT front rotating air seals. The compliance intervals are based 
upon risk analysis. The actions would be required to be accomplished in 
accordance with the SBs described previously.

Economic Analysis

    There are approximately 121 engines of the affected design in the 
worldwide fleet. The FAA estimates that 13 engines installed on 
aircraft of US registry would be affected by this proposed AD, that it 
would take approximately 300 work hours per engine to accomplish the 
proposed actions, and that the average labor rate is $60 per work hour. 
Based on these figures, the total cost impact of the proposed AD on US 
operators is estimated to be $234,000.

Regulatory Impact

    This proposal does not have federalism implications, as defined in 
Executive Order No. 13132, because it would not have a substantial 
direct effect 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. Accordingly, 
the FAA has not consulted with state authorities prior to publication 
of this proposal.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, 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 copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting 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.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

    CFM International: Docket No. 99-NE-57-AD.
    Applicability: CFM International (CFMI) CFM56-2, -2A, -2B, -3, -
3B, and -3C series turbofan engines, installed on but not limited to 
McDonnell Douglas DC-8 series, Boeing 737 series, as well as Boeing 
E-3, E-6, and KC-135 (Military) series airplanes.

    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 (c) 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 cracks in the bolt holes of high pressure turbine 
(HPT) front rotating air seals, which can lead to an uncontained 
engine failure and damage to the aircraft, accomplish the following:

One-Time Eddy Current Inspections (ECI) Based Upon Engine Model and 
Thrust Ratings

    (a) Perform a one-time ECI for cracks in the bolt holes of HPT 
front rotating air seals, part number 1282M72P03, and, if necessary, 
replace with serviceable parts, as follows:

CFM56-3 Series

    (1) For CFM56-3-B1 engine nameplate models with HPT front 
rotating air seals listed by serial number (S/N) in paragraph 
1.A(1), Effectivity, of CFMI CFM56-3/3B/3C Service Bulletin (SB) 72-
922, dated November 12, 1999, inspect in accordance with the 
procedures described in Paragraph 2, Accomplishment Instructions, of 
that SB, and in accordance with the intervals listed in paragraph 
(a)(4)(i) or (a)(4)(ii) of this AD, as applicable.
    (2) For CFM56-3B-2 models with maximum thrust limited to 20,100 
or 18,500 pounds by the FMC and aircraft flight manual AFM, with HPT 
front rotating air seals listed by S/N in paragraph 1.A(1), 
Effectivity, of CFMI CFM56-3/3B/3C SB 72-922, dated November 12, 
1999, inspect in accordance with the procedures described in 
Paragraph 2, Accomplishment Instructions, of that SB, and in 
accordance with the intervals listed in paragraph (a)(4)(i) or 
(a)(4)(ii) of this AD, as applicable.
    (3) For CFM56-3C-1 models with maximum thrust limited to 20,100 
or 18,500 pounds by the FMC and AFM, , with HPT front rotating air 
seals listed by S/N in paragraph 1.A(1), Effectivity, of CFMI CFM56-
3/3B/3C SB 72-922, dated November 12, 1999, inspect in accordance 
with the procedures described in Paragraph 2, Accomplishment 
Instructions, of that SB, and in accordance with the intervals 
listed in paragraph (a)(4)(i) or (a)(4)(ii), as applicable.

Compliance Times for (a)(1), (a)(2), and (a)(3)

    (4) Use the following compliance times for the engine models 
listed in paragraphs (a)(1), (a)(2), and (a)(3) of this AD:
    (i) For HPT front rotating air seals with less than 10,000 
cycles since new (CSN) on the effective date of this AD, inspect at 
the next engine shop visit after accumulating 4,000 CSN, not to 
exceed 13,000 CSN.
    (ii) For HPT front rotating air seals with 10,000 CSN or more on 
the effective date of this AD, inspect at the next engine shop visit 
prior to accumulating 3,000 cycles-in-service (CIS) after the 
effective date of this AD, or prior to accumulating 20,000 CSN, 
whichever occurs first.
    (5) For CFM56-3B-2 engine nameplate models, with HPT front 
rotating air seals listed by S/N in paragraph 1.A(1), Effectivity, 
of CFMI CFM56-3/3B/3C SB 72-922, dated November 12, 1999, inspect in 
accordance with the procedures described in Paragraph 2, 
Accomplishment Instructions, of that SB, and in accordance with the 
intervals listed in paragraphs (a)(7)(i), or (a)(7)(ii) of this AD, 
as applicable.
    (6) For CFM56-3C-1 models with maximum thrust limited to 22,100 
pounds by the FMC and AFM, with HPT front rotating air seals listed 
by S/N in paragraph 1.A(1), Effectivity, of CFMI CFM56-3/3B/3C SB 
72-922, dated November 12, 1999, inspect in accordance with the 
procedures described in Paragraph 2, Accomplishment Instructions, of 
that SB, and in accordance with the intervals listed in paragraphs 
(a)(7)(i), or (a)(7)(ii) of this AD, as applicable.

Compliance Times for (a)(5) and (a)(6)

    (7) Use the following compliance times for the engine models 
listed in paragraphs (a)(5) and (a)(6) of this AD:
    (i) For HPT front rotating air seals with less than 9,800 CSN on 
the effective date of this AD, inspect at the next engine shop visit 
after accumulating 4,000 CSN, not to exceed 12,800 CSN.
    (ii) For HPT front rotating air seals with 9,800 CSN or more on 
the effective date of this AD, inspect at the next engine shop visit 
prior to accumulating 3,000 CIS after the effective date of this AD, 
or prior to accumulating 15,800 CSN, whichever occurs first.
    (8) For CFM56-3C-1 engine nameplate models, with HPT front 
rotating air seals listed by S/N in paragraph 1.A(1), Effectivity, 
of CFMI CFM56-3/3B/3C SB 72-922, dated

[[Page 69430]]

November 12, 1999, inspect in accordance with the procedures 
described in Paragraph 2, Accomplishment Instructions, of that SB, 
as follows:
    (i) For HPT front rotating air seals with less than 9,100 CSN on 
the effective date of this AD, inspect at the next engine shop visit 
after accumulating 4,000 CSN, not to exceed 12,100 CSN.
    (ii) For HPT front rotating air seals with 9,100 CSN or more on 
the effective date of this AD, inspect at the next engine shop visit 
prior to accumulating 3,000 CIS after the effective date of this AD, 
or prior to accumulating 15,100 CSN, whichever occurs first.

Uninstalled Parts

    (9) Prior to installation in CFM56-3/3B/3C series engines, 
inspect uninstalled parts listed by S/N in paragraph 1.A(1), 
Effectivity, of CFMI CFM56-3/3B/3C SB 72-922, dated November 12, 
1999, in accordance with Paragraph 2, Accomplishment Instructions, 
of that SB.

CFM56-2 Series

    (10) For CFM56-2 engine nameplate models, with HPT front 
rotating air seals listed by S/N in paragraph 1.A(1), Effectivity, 
of CFMI CFM56-2 SB 72-869, dated November 12, 1999, inspect in 
accordance with the procedures described in Paragraph 2, 
Accomplishment Instructions, of that SB, as follows:
    (i) For HPT front rotating air seals with less than 9,100 CSN on 
the effective date of this AD, inspect at the next engine shop visit 
after accumulating 4,000 CSN, not to exceed 10,100 CSN.
    (ii) For HPT front rotating air seals with 9,100 CSN or more on 
the effective date of this AD, inspect at the next engine shop visit 
prior to accumulating 1,000 CIS after the effective date of this AD, 
or prior to accumulating 13,100 CSN, whichever occurs first.

Uninstalled Parts

    (11) Prior to installation in CFM56-2 series engines,  inspect  
uninstalled  parts  listed  by S/N in paragraph 1.A(1), Effectivity, 
of CFMI CFM56-2 SB 72-869, dated November 12, 1999, in accordance 
with Paragraph 2, Accomplishment Instructions, of that SB.

CFM56-2A Series

    (12) For CFM56-2A engine nameplate models, with HPT front 
rotating air seals listed by S/N in paragraph 1.A(1), Effectivity, 
of CFM56-2A SB 72-470, dated November 12, 1999, inspect in 
accordance with the procedures described in Paragraph 2, 
Accomplishment Instructions, of that SB, after accumulating 3,000 
CSN but before accumulating 6,000 CSN.

Uninstalled Parts

    (13) Prior to installation in CFM56-2A series engines, inspect 
uninstalled parts listed by S/N in paragraph 1.A(1), Effectivity, of 
CFMI CFM56-2A SB 72-470, dated November 12, 1999, in accordance with 
the procedures described in Paragraph 2, Accomplishment 
Instructions, of that SB.

CFM56-2B Series

    (14) For CFM56-2B engine nameplate models, with HPT front 
rotating air seals listed by S/N in paragraph 1.A(1), Effectivity, 
of CFM56-2B SB 72-611, dated November 12, 1999, inspect in 
accordance with the procedures described in Paragraph 2, 
Accomplishment Instructions, of that SB, after accumulating 3,000 
CSN but before accumulating 6,000 CSN.

Uninstalled Parts

    (15) Prior to installation in CFM56-2B series engines, inspect 
uninstalled parts listed by S/N in paragraph 1.A(1), Effectivity, of 
CFMI CFM56-2B SB 72-611, dated November 12, 1999, in accordance with 
the procedures described in Paragraph 2, Accomplishment 
Instructions, of that SB.

Replace Cracked Parts

    (16) Prior to further flight, replace cracked HPT front rotating 
air seals with serviceable parts.

Definition

    (b) For the purpose of this AD, an engine shop visit is defined 
as the next time, after the effective date of this AD, an engine is 
in the shop for the purpose of maintenance or inspection.

Alternative Methods of Compliance

    (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 (ECO). 
Operators shall submit their request through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, ECO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the ECO.

Ferry Flights

    (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) to operate the aircraft to a location where 
the inspection requirements of this AD can be accomplished.

    Issued in Burlington, Massachusetts, on December 7, 1999.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 99-32194 Filed 12-10-99; 8:45 am]
BILLING CODE 4910-13-P