Airworthiness Directives; Rolls-Royce plc RB211-535E4 and -535E4- B Series Turbofan Engines

[Federal Register Volume 62, Number 22 (Monday, February 3, 1997)]
[Rules and Regulations]
[Pages 4899-4900]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-1701]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-ANE-09; Amendment 39-9897; AD 97-02-12]
RIN 2120-AA64


Airworthiness Directives; Rolls-Royce plc RB211-535E4 and -535E4-
B Series Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to Rolls-Royce plc RB211-535E4 and -535E4-B series turbofan 
engines, that requires installation of an improved fuel flow governor 
that incorporates revised minimum compressor discharge P4 stop 
settings. This amendment is prompted by reports of engine rundowns 
during low idle descent during icing conditions. The actions specified 
by this AD are intended to prevent compressor stall and subsequent 
engine rundown on one or both engines.

DATES: Effective April 4, 1997.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of April 4, 1997.

ADDRESSES: The service information referenced in this AD may be 
obtained from Rolls-Royce plc, P.O. Box 31, Moor Lane, Derby, DE248BJ, 
United Kingdom; telephone 1332-249428, fax 1332-249423. This 
information may be examined at the Federal Aviation Administration 
(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.

FOR FURTHER INFORMATION CONTACT: Daniel Kerman, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (617) 
238-7130, fax (617) 238-7199.

SUPPLEMENTARY INFORMATION: 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) RB211-535 
series turbofan engines was published in the Federal Register on June 
12, 1996 (61 FR 29697). That action proposed to require installation of 
an improved Fuel Flow Governor (FFG) that incorporate revised minimum 
compressor discharge P4 stop settings. This revised setting will raise 
the steady state low idle schedule above the idle conditions 
experienced during any of the prior engine rundown events. This 
schedule increase will result in a substantial increase in Intermediate 
Pressure Compressor (IPC) stall margin, a moderate increase in High 
Pressure Compressor (HPC) stall margin, as well as provide the 
additional benefit of increased ice accretion tolerance due to 
increased compressor airflow and increased rotor speed. This action 
must be accomplished within 9 calendar months after the effective date 
of this AD. The FAA has determined the calendar end-date based on the 
time interval required for fleet modification. The actions would be 
required to be accomplished in accordance with R-R Mandatory (SB) No. 
RB.211-73-B869, Revision 1, dated May 24, 1996.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.
    One commenter states that the proposed AD should be modified to 
eliminate the shop visit requirement and to impose a calendar end-date 
for compliance with the proposed FFG modification. The FAA concurs, and 
has revised this final rule to delete the shop visit requirement. The 
FAA has determined that the shop visit requirement is not necessary and 
that a calendar end-date will assure an adequate level of safety.
    One commenter states that the compliance period for the proposed AD 
should be extended from 9 months to one year. The commenter bases this 
request on the fact that there are limited facilities available to 
modify the FFG. The FAA does not concur. The manufacturer has 
established sufficient inventory and facility capability to implement 
the modification program within 9 months after the effective date of 
the final rule AD. The FAA also notes that the burden on the current 
inventory and facilities will be minimized because a large population 
of operators have already voluntarily complied with the proposed FFG 
modification.
    One commenter states that the modification of the FFG, as required 
by the proposed AD, on one engine for each aircraft, should be 
sufficient for terminating action to AD 96-04-11, which required 
selecting anti-ice prior to initiating descent. The FAA does not 
concur. The FAA is concerned that under the circumstances in which a 
rundown occurs, there could be excessive crew workload, and that this 
increased workload could lead to potentially inappropriate actions by 
the flight crew. The FAA has determined that the interests of the 
flying public are best served by requiring the proposed FFG 
modification on both engines to preclude this excessive crew workload.
    After careful review of the available data, including the comments 
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.
    There are approximately 770 engines of the affected design in the 
worldwide fleet. The FAA estimates that 381 engines installed on 
aircraft of U.S. registry will be affected by this AD, that it will 
take approximately 3 work hours per engine to accomplish the required 
actions, and that the average labor rate is $60 per work hour. The 
affected FFGs will be modified to incorporate the changes required by 
this AD on a free-of-charge basis per engine. Based on these figures, 
the total cost impact of the AD on U.S. operators is estimated to be 
$68,580.
    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

[[Page 4900]]

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 USC 106(g), 40113, 44701.


Sec. 39.13  [Amended]

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

97-02-12  Rolls-Royce plc: Amendment 39-9897. Docket 96-ANE-09.

    Applicability: Rolls-Royce plc. (R-R) Models RB211-535E4 and -
535E4-B turbofan engines installed on Boeing 757-200 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 (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 compressor stall and subsequent engine rundown on one 
or both engines, accomplish the following:
    (a) No later than 9 calendar months after the effective date of 
this AD, install a fuel flow governor (FFG) that incorporates a 
revised minimum compressor discharge P4 stop setting, in accordance 
with R-R Mandatory Service Bulletin (SB) No. RB.211-73-B869, 
Revision 1, dated May 24, 1996.
    (b) Installation of improved FFGs on both engines for each 
Boeing 757 aircraft in accordance with paragraph (a) of this AD 
constitutes terminating action to the requirements of AD 96-04-11.
    (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. 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 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.

    (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 requirements of this AD can be accomplished.
    (e) The actions required by this AD shall be done in accordance 
with the following R-R Mandatory SB:

------------------------------------------------------------------------
         Document No.              Pages       Revision        Date     
------------------------------------------------------------------------
RB.211-73-B869................  1-4          1            May 24, 1996. 
                                5-9          Original     February 12,  
                                                           1996.        
Supplement....................  1            Original     February 12,  
                                                           1996.        
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Total Pages: 10.                                                        

    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 Rolls-Royce plc, P.O. Box 31, 
Moor Lane, Derby, DE248BJ, United Kingdom; telephone 1332-249428, 
fax 1332-249423. Copies may be inspected 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.
    (f) This amendment becomes effective on April 4, 1997.
    Issued in Burlington, Massachusetts, on January 13, 1997.

Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 97-1701 Filed 1-31-97; 8:45 am]
BILLING CODE 4910-13-U

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