[Federal Register: March 26, 1998 (Volume 63, Number 58)]
[Proposed Rules]               
[Page 14652-14654]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr26mr98-28]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-311-AD]
RIN 2120-AA64

 
Airworthiness Directives; Boeing Model 757-200 Series Airplanes 
Powered by Rolls-Royce RB211-535E4/E4B 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 certain Boeing Model 757-200 
series airplanes. This proposal would require repetitive inspections to 
detect cracking of the acoustic panels in the engine inlet, and repair, 
if necessary. This proposal also would require eventual replacement of 
the existing engine inlet with a new inlet, which, when accomplished, 
would terminate the repetitive inspections. This proposal is prompted 
by reports of cracking of acoustic panels in the engine inlet, and 
incidents of pieces of the panels breaking off and being ingested into 
the engine. The actions specified by the proposed AD are intended to 
detect and correct cracking of the acoustic panels in the engine inlet, 
which could result in reduced structural integrity of the engine inlet, 
and consequent engine shutdown or surge; or in the event of a fan blade 
failure, separation of the inlet from the engine.

DATES: Comments must be received by May 11, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 97-NM-311-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056.

[[Page 14653]]

Comments may be inspected at this location between 9:00 a.m. and 3:00 
p.m., Monday through Friday, except Federal holidays.
    The service information referenced in the proposed rule may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Kathrine H. Rask, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-1547; fax (425) 227-1181.

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 shall identify the Rules Docket number 
and be submitted in triplicate 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 97-NM-311-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, Transport Airplane Directorate, ANM-114, Attention: Rules 
Docket No. 97-NM-311-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports of cracking of the acoustic panels in 
the engine inlets of certain Boeing Model 757-200 series airplanes. In 
several cases, the areas of cracking are large enough to affect the 
structural integrity of the engine inlets. These cracked areas could 
detach and be ingested into the engine, which could cause internal 
damage to the engine and consequent engine shutdown. The cracked areas 
also could sag and disturb the airflow into the engine, which could 
cause the engine to surge and lose power. The FAA has received reports 
of two incidents in which portions of the engine inlet acoustic panels 
have been ingested into the engine; in one of these incidents, the 
ingested piece caused high vibration in the engine and damage to the 
leading edge tip of the fan blade.
    The cracking of the acoustic panels has been attributed to an 
inherent design problem of the engine inlet, in which the resonance of 
the honeycomb structure at the core of the acoustic panels coincides 
with the passing frequency of the fan blade, which causes the honeycomb 
structure to crack. Because of the nature of this condition, the FAA 
has concluded that such cracking may exist or develop on other 
airplanes of this type design.
    Cracking of the acoustic panels in the engine inlet, if not 
detected and corrected, could result in reduced structural integrity of 
the engine inlet, and consequent engine shutdown or surge; or in the 
event of a fan blade failure, separation of the inlet from the engine.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Rolls-Royce Service Bulletin 
RB.211-71-B480, Revision 1, dated August 15, 1997, which describes 
procedures for repetitive detailed inspections to detect cracking of 
the acoustic panels in the engine inlet, and repair, if necessary.
    The FAA also has reviewed and approved Rolls-Royce Service Bulletin 
RB.211-71-9909, Revision 1, dated May 26, 1995, and Rolls-Royce Service 
Bulletin RB.211-71-9958, Revision 1, dated March 18, 1994, which 
describe procedures for replacing the existing engine inlet assembly 
with a new engine inlet assembly that incorporates improved acoustic 
panels. Such replacement eliminates the need for the repetitive 
inspections. Accomplishment of this replacement, as described in these 
service bulletins, is intended to adequately address the identified 
unsafe condition.

Explanation of Requirements of Proposed Rule

    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 accomplishment of the actions specified in 
the service bulletins described previously, except as discussed below.

Differences Between Proposed Rule and Service Bulletin

    Operators should note that, for airplane on which damage is found 
that exceeds the acceptance standards provided in paragraph 2.A. of 
Appendix 1 of Rolls-Royce Service Bulletin RB.211-71-B480, Revision 1, 
dated August 15, 1997, the service bulletin specifies that the 
manufacturer should be contacted for disposition of such damage. 
However, this proposed AD would not require that the manufacturer be 
contacted, but rather that those damaged engine inlets be replaced 
prior to further flight.

Cost Impact

    There are approximately 52 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 24 airplanes of U.S. registry 
would be affected by this proposed AD.
    Assuming both engines have inlets on which the improved acoustic 
panels have not been installed, it would take approximately 3 work 
hours per airplane (1.5 work hours per engine) to accomplish the 
proposed inspection, at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of this proposed inspection on 
U.S. operators is estimated to be $4,320, or $180 per airplane, per 
inspection cycle.
    Assuming both engines have inlets on which the improved acoustic 
panels have not been installed, it would take approximately 4 work 
hours per airplane (2 work hours per engine) to accomplish the proposed 
replacement, at an average labor rate of $60 per work hour. Required 
parts would be provided by the engine manufacturer at no cost to the 
operator. Based on these figures, the cost impact of this modification 
on U.S. operators is estimated to be $5,760, or $240 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the proposed requirements 
of this AD action, and that no operator would accomplish those actions 
in the future if this AD were not adopted.

[[Page 14654]]

Regulatory Impact

    The regulations proposed herein would 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 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    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:
Boeing: Docket 97-NM-311-AD.

    Applicability: Model 757-200 series airplanes; equipped with 
Rolls-Royce RB211-535E4/E4B engines, fitted with nose cowls having 
serial numbers 9001 through 9124 inclusive; certificated in any 
category.

    Note 1: This AD applies to each airplane 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 airplanes 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 detect and correct cracking of the acoustic panels in the 
engine inlet, which could result in reduced structural integrity of 
the engine inlet, and consequent engine shutdown or surge; or in the 
event of a fan blade failure, separation of the inlet from the 
engine; accomplish the following:
    (a) Within 60 days after the effective date of this AD, perform 
a detailed inspection to detect cracking of the acoustic panels in 
the engine inlet, in accordance with Rolls-Royce Service Bulletin 
RB.211-71-B480, Revision 1, dated August 15, 1997.
    (1) If no cracking is detected, repeat the inspection thereafter 
at intervals not to exceed 650 hours time-in-service.
    (2) If any cracking is detected, accomplish the requirements of 
either paragraph (a)(2)(i) or (a)(2)(ii), as applicable.
    (i) If cracking is within the acceptance standards provided in 
paragraph 2.A. of Appendix 1 of the service bulletin, repair within 
350 hours time-in-service, in accordance with the service bulletin. 
Thereafter, repeat the inspection required by paragraph (a) of this 
AD at intervals not to exceed 650 hours time-in-service.
    (ii) If cracking is outside the acceptance standards provided in 
paragraph 2.A. of Appendix 1 of the service bulletin, prior to 
further flight, replace the engine inlet with a new engine inlet 
that incorporates improved acoustic panels, in accordance with 
Rolls-Royce Service Bulletin RB.211-71-9909, Revision 1, dated May 
26, 1995, and Rolls-Royce Service Bulletin RB.211-71-9958, Revision 
1, dated March 18, 1994. No further action is required by this AD 
for that engine inlet.
    (b) Within 18 months after the effective date of this AD, 
replace both existing engine inlets with new inlets that incorporate 
improved acoustic panels, in accordance with Rolls-Royce Service 
Bulletin RB.211-71-9909, Revision 1, dated May 26, 1995, and Rolls-
Royce Service Bulletin RB.211-71-9958, Revision 1, dated March 18, 
1994. Accomplishment of such replacement constitutes terminating 
action for the requirements of this AD.
    (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, Seattle Aircraft Certification 
Office (ACO), FAA, Transport Airplane Directorate. Operators shall 
submit their requests through an appropriate FAA Principal 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Seattle ACO.
    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (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 airplane to a location where 
the requirements of this AD can be accomplished.

    Issued in Renton, Washington, on March 19, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-7880 Filed 3-25-98; 8:45 am]
BILLING CODE 4910-13-U