[Federal Register Volume 64, Number 79 (Monday, April 26, 1999)]
[Proposed Rules]
[Pages 20226-20229]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-10346]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-133-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-100, -200, -300, -400, 
and -500 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Supplemental notice of proposed rulemaking; reopening of 
comment period.

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SUMMARY: This document revises an earlier proposed airworthiness 
directive (AD), which would have superseded an existing AD that is 
applicable to certain Boeing Model 737-100, -200, -300, -400, and -500 
series airplanes. The existing AD currently requires an inspection of 
reworked aileron/elevator power control units (PCU's) and rudder PCU's 
to determine if reworked PCU manifold cylinder bores containing chrome 
plating are installed, and replacement of the cylinder bores with bores 
that have been reworked using the oversize method or the steel sleeve 
method, if necessary. This action, among other items, revises the 
previously proposed rule by expanding the applicability of the existing 
AD to include airplanes equipped with certain rudder PCU's. The actions 
specified by this new proposed AD are intended to prevent a reduced 
rate of movement of the elevator, aileron, or rudder due to 
contamination of hydraulic fluid from chrome plating chips; such 
reduced rate of movement, if not corrected, could result in reduced 
controllability of the airplane.

DATES: Comments must be received by May 21, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 97-NM-133-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. 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: Don Kurle, Senior Engineer, Systems 
and Equipment Branch, ANM-130S, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2798; 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

[[Page 20227]]

statement is made: ``Comments to Docket Number 97-NM-133-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-133-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to add an airworthiness directive (AD), applicable to 
certain Boeing Model 737-100, -200, -300, -400, and -500 series 
airplanes, was published as a notice of proposed rulemaking (NPRM) in 
the Federal Register on February 19, 1998 (63 FR 8369). That NPRM would 
have superseded AD 97-09-14, amendment 39-10010 (62 FR 24008, May 2, 
1997), to continue to require an inspection of reworked aileron/
elevator power control units (PCU's) and rudder PCU's to determine if 
reworked PCU manifold cylinder bores containing chrome plating are 
installed, and replacement of the cylinder bores with bores that have 
been reworked using the oversize method or the steel sleeve method, if 
necessary. That NPRM would have expanded the applicability of the 
existing AD to include airplanes equipped with rudder PCU's having part 
number (P/N) 65C37052-(). That NPRM also would have revised the 
existing AD to exclude rudder PCU's (in addition to aileron/elevator 
actuators) having serial numbers that contain ``ss'' from the 
requirements of the proposed AD. That NPRM was prompted by a review of 
the design of the flight control systems on Model 737 series airplanes. 
The actions specified in that NPRM were intended to prevent a reduced 
rate of movement of the elevator, aileron, or rudder due to 
contamination of hydraulic fluid from chrome plating chips; such 
reduced rate of movement, if not corrected, could result in reduced 
controllability of the airplane.

Actions Since Issuance of Previous Proposal

    Due consideration has been given to the comments received in 
response to the NPRM.
    Two commenters support the proposed rule.

Requests To Add a Certain Rudder PCU to the Requirements of the 
Proposed AD

    Several commenters state that rudder PCU's having P/N 65C37053-( ) 
are subject to the identified unsafe condition, and therefore, should 
be included in the applicability statement and paragraphs (d) and (f) 
of the proposed AD. The commenters note that AD 97-14-04, amendment 39-
10061 (62 FR 35068, June 30, 1997), requires replacement of rudder 
PCU's having P/N 65C37052-( ) with PCU's having P/N 65C37053-( ). The 
commenters point out that PCU's having P/N 65C37053-( ) are upgraded 
from the same base PCU as the PCU's having P/N 65C37052-( ). The FAA 
concurs. The FAA inadvertently omitted PCU, P/N 65C37053-( ), from the 
requirements of the proposed AD. Therefore, the FAA has revised the 
applicability statement and paragraphs (d) and (f) of the supplemental 
NPRM accordingly.

Request To Allow Replacement With New Manifolds

    One commenter requests that the FAA revise paragraphs (b) and (e) 
of the proposed AD to allow PCU manifolds containing chrome plated 
cylinder bores to be replaced with new manifolds, in addition to bores 
that have been reworked using the oversize method or the steel method. 
The commenter states that the original equipment manufacturer has not 
produced PCU manifolds with chrome plated cylinder bores since 1985. 
The FAA concurs. The FAA has confirmed with Boeing that manifolds with 
chrome plated bores have not been produced since 1985. Therefore, the 
FAA has revised the requirements of paragraphs (b) and (e) of the 
supplemental NPRM to include an option of replacing the cylinder bores 
containing chrome plating with PCU manifold cylinder bores that were 
manufactured after December 31, 1985, in lieu of replacing the cylinder 
bores that have been reworked using the oversize method or steel sleeve 
method. In addition, the proposed requirements of those paragraphs have 
been revised to allow operators to replace the rudder, aileron, or 
elevator PCU with a certain PCU, as applicable.

Request To Delete Reference to Incorrect Service Letter

    One commenter requests that the sentence ``accomplish the 
replacement in accordance with the service letter'' be deleted from 
paragraphs (b) and (e) of the proposed AD. The commenter states the 
Boeing Service Letter 737-SL-27-30, dated April 1, 1985, does not 
contain any replacement instructions. The commenter contends that the 
service letter recommends the removal of the chrome bores and advises 
of alternative repair methods.
    The FAA concurs partially. The FAA acknowledges that the subject 
service letter does not contain replacement procedures for 
accomplishment of the requirements of paragraphs (b) and (e) of the AD. 
The FAA has consulted with Boeing and determined that the following 
chapters of the Boeing 737 Airplane Maintenance Manual (AMM) contain 
the appropriate procedures for accomplishment of the actions specified 
in paragraphs (b) and (e) of this AD:
     Chapter 27-11-71 (for Model 737-100, -200, -300, -400, and 
-500 series airplanes) for replacement of the aileron PCU;
     Chapter 27-31-101 (for Model 737-100 and -200 series 
airplanes), and Chapter 27-31-14 (for Model 737-300, -400, and -500 
series airplanes) for replacement of the elevator PCU; and
     Chapter 27-21-91 (for Model 737-100, -200, -300, -400, and 
-500 series airplanes) for replacement of the rudder PCU.
    Therefore, the FAA has revised paragraphs (b) and (e) of the 
supplemental NPRM to reference these chapters of the AMM as the 
appropriate sources of service information for accomplishment of the 
actions specified in paragraphs (b)(1), (b)(2), (b)(3), (e)(1), and 
(e)(2), as applicable.

Requests To Accept Previously Approved Alternative Method of 
Compliance (AMOC)

    Two commenters request that the inspection method specified in 
Boeing Service Letter 737-SL-27-120, dated January 28, 1998, be 
considered acceptable for compliance with the inspection requirements 
of paragraphs (a) and (d) of the proposed AD. One of these commenters 
states that the FAA approved this inspection method as an AMOC in 
accordance with AD 97-09-14. The other commenter states that the 
subject inspection method can be accomplished without removing the 
PCU's from the airplanes and disassembling them. The FAA concurs with 
the commenters' request. The FAA has added a new paragraph (g)(2) to 
the supplemental NPRM to include a statement that reflects this point.

Conclusion

    Since some of these changes expand the scope of the originally 
proposed rule, the FAA has determined that it is necessary to reopen 
the comment period to provide additional opportunity for public 
comment.

Cost Impact

    There are approximately 2,675 Model 737 series airplanes of the 
affected design in the worldwide fleet. The FAA

[[Page 20228]]

estimates that 1,091 airplanes of U.S. registry would be affected by 
this proposed AD.
    The actions that are currently required by AD 97-09-14, and 
retained in this proposed AD, take approximately 5 work hours per 
airplane to accomplish, at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of the currently required 
actions on U.S. operators is estimated to be $327,300, or $300 per 
airplane.
    The new actions that are proposed in this AD action would take 
approximately 5 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact of the proposed requirements of this AD on U.S. operators is 
estimated to be $300 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.

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 removing amendment 39-10010 (62 FR 
24008, May 2, 1997), and by adding a new airworthiness directive (AD), 
to read as follows:

Boeing:  Docket 97-NM-133-AD. Supersedes AD 97-09-14, Amendment 39-
10010.

    Applicability: Model 737-100, -200, -300, -400, and -500 series 
airplanes, certificated in any category; equipped with the following 
power control units (PCU):
     a rudder PCU, having part number (P/N) 65-44861-( ), P/
N 65C37052-( ), or P/N 65C37053-( ) (except those having serial 
numbers that contain ``ss''), and a serial number less than 1252A; 
or
     an aileron or elevator PCU having P/N 65-44761-( ) 
(except those having serial numbers that contain an ``ss'') and a 
serial number less than 5360A.

    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 (g)(1) 
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 a reduced rate of movement of the elevator, aileron, 
or rudder, which, if not corrected, could result in reduced 
controllability of the airplane, accomplish the following:
    (a) Perform an inspection of reworked or overhauled aileron and 
elevator PCU's having P/N 65-44761-( ) (except those having serial 
numbers that contain an ``ss''), and a serial number less than 
5360A; and rudder PCU's having P/N 65-44861-( ) and a serial number 
less than 1252A (except those having serial numbers that contain 
``ss''); to determine if reworked PCU manifold cylinder bores 
containing chrome plating are installed, in accordance with Boeing 
Service Letter 737-SL-27-30, dated April 1, 1985. Accomplish the 
inspection at the earlier of the times specified in paragraphs 
(a)(1) and (a)(2) of this AD.
    (1) Within 5 years or 15,000 flight hours after June 6, 1997 
(the effective date of AD 97-09-14, amendment 39-10010), whichever 
occurs first.
    (2) At the next time the PCU is sent to a repair facility.
    (b) If any reworked PCU manifold cylinder bores containing 
chrome plating are found to be installed during the inspection 
required by paragraph (a) of this AD: Prior to further flight, 
accomplish the actions specified in paragraph (b)(1), (b)(2), or 
(b)(3) of this AD in accordance with Chapter 27-11-71 (for Model 
737-100, -200, -300, -400, and -500 series airplanes), Chapter 27-
31-101 (for Model 737-100 and -200 series airplanes), or Chapter 27-
31-14 (for Model 737-300, -400, and -500 series airplanes) of Boeing 
737 Airplane Maintenance Manual (AMM); as applicable.
    (1) Replace the cylinder bores with bores that were manufactured 
after December 31, 1985, or with bores that have been reworked using 
the oversize method or the steel sleeve method specified in Boeing 
Service Letter 737-SL-27-30, dated April 1, 1985.
    (2) Replace the aileron or elevator PCU with a PCU containing 
the letters ``ss'' in its serial number or with a PCU having a 
serial number of 5306A or higher.
    (3) Replace the rudder PCU with a PCU containing the letters 
``ss'' in its serial number or with a PCU having a serial number of 
1252A or higher.
    (c) As of June 6, 1997, no person shall install a reworked PCU 
manifold cylinder bore containing chrome plating on an aileron or 
elevator PCU having P/N 65-44761-( ), or on a rudder PCU having P/N 
65-44861-( ), on any airplane unless the cylinder bore has been 
reworked using the oversize method or the steel sleeve method 
specified in Boeing Service Letter 737-SL-27-30, dated April 1, 
1985.
    (d) Perform an inspection of reworked or overhauled rudder PCU's 
having P/N 65C37052-( ) or P/N 65C37053-( ) and a serial number less 
than 1252A (except those having serial numbers that contain ``ss'') 
to determine if reworked PCU manifold cylinder bores containing 
chrome plating are installed, in accordance with Boeing Service 
Letter 737-SL-27-30, dated April 1, 1985. Accomplish the inspection 
at the earlier of the times specified in paragraphs (d)(1) and 
(d)(2) of this AD.
    (1) Within 5 years or 15,000 flight hours after the effective 
date of this AD, whichever occurs first.
    (2) At the next time the PCU is sent to a repair facility.
    (e) If any reworked PCU manifold cylinder bores containing 
chrome plating are found to be installed during the inspection 
required by paragraph (d) of this AD: Prior to further flight, 
accomplish the actions specified in paragraph (e)(1) or (e)(2) of 
this AD in accordance with Chapter 27-21-91 (for Model 737-100, -
200, -300, -400, and -500 series airplanes) of Boeing 737 Airplane 
Maintenance Manual (AMM).
    (1) Replace the cylinder bores with bores that were manufactured 
after December 31, 1985, or with bores that have been reworked using 
the oversize method or the steel sleeve method specified in Boeing 
Service Letter 737-SL-27-30, dated April 1, 1985.
    (2) Replace the rudder PCU with a PCU containing the letters 
``ss'' in its serial

[[Page 20229]]

number or with a PCU having a serial number of 1252A or higher.
    (f) As of the effective date of this AD, no person shall install 
a reworked PCU manifold cylinder bore containing chrome plating on a 
rudder PCU having P/N 65C37052-( ) or 
P/N 65C37053-( ) on any airplane unless the cylinder bore has been 
reworked using the oversize method or the steel sleeve method 
specified in Boeing Service Letter 737-SL-27-30, dated April 1, 
1985.
    (g)(1) 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.
    (g)(2) Alternative methods of compliance, approved previously in 
accordance with AD 97-09-14, amendment 39-10010, are approved as 
alternative methods of compliance with this AD.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (h) 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 April 20, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-10346 Filed 4-23-99; 8:45 am]
BILLING CODE 4910-13-P