AD 2003-11-19

[Federal Register Volume 68, Number 112 (Wednesday, June 11, 2003)]
[Rules and Regulations]
[Pages 34781-34786]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 03-13976]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NM-41-AD; Amendment 39-13178; AD 2003-11-19]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 727-100 and 727-200 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 727-100 and 727-200 series 
airplanes, that requires, under certain conditions, replacement of the 
installed autopilot pitch control computer with a modified computer, 
testing of the modified system, and revision of the Airplane Flight 
Manual (AFM). The actions specified by this AD are intended to prevent 
undesirable and potentially dangerous pitch oscillations during coupled 
instrument landing system (ILS) approaches. This AD is intended to 
address the identified unsafe condition.

DATES: Effective July 16, 2003.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of July 16, 2003.

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplane Group, PO Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the Federal 
Aviation Administration (FAA), Transport Airplane Directorate, Rules 
Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of 
the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.

FOR FURTHER INFORMATION CONTACT: Thanh Truong, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-
4056; telephone (425) 917-6486; fax (425) 917-6590.

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 certain Boeing Model 727-100 and 
727-200 series airplanes was published in the Federal Register on 
September 10, 2001 (66 FR 46968). That action proposed to require 
replacement of the installed autopilot pitch control computer with a 
modified computer, testing of the modified system, and revision of the 
Airplane Flight Manual (AFM).

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Support for the Proposed AD

    One operator reports that the actions specified in the proposed AD 
have been incorporated on all of its airplanes.

Request To Withdraw AD

    One operator asserts that accomplishment of the actions specified 
in the proposed AD would not eliminate the identified unsafe condition, 
and suggests that pilot training and procedures would eliminate 
unstable category II approaches by autopilot disconnect. The FAA infers 
that the commenter is requesting withdrawal of the proposed AD.
    The FAA does not agree. The unsafe condition is related to the 
accident described in the proposed AD involving a Model 727 series 
airplane during a coupled instrument landing system (ILS) category II 
approach. The circumstances surrounding that accident led in part to 
the issuance of this AD. The divergent pitch oscillations of the 
airplane resulted from an improper autopilot desensitization rate and 
contributed to the accident. This AD addresses the improper autopilot 
desensitization rate. The AFM revisions required by this AD provide 
data to the flightcrew regarding certain limitations, such as autopilot 
disconnect, inherent in the design of Sperry SP-50 and SP-150 
autopilots. Observing these limitations will help the flightcrew take 
the appropriate action necessary for a successful landing or go-around.

Request To Delay AD Issuance Pending Further Study

    One operator requests that issuance of the AD be delayed until 
further studies, as described in the proposed AD, can be completed. The 
proposed AD describes additional studies in process that are intended 
to develop appropriate limits for flap settings and airspeeds and to 
investigate other aspects such as winds and glideslope angles as 
possible contributors to the unsafe condition. The commenter requests 
that the studies be completed before the proposed AFM revisions and 
modifications are mandated.
    The FAA does not agree. If the results of the studies ultimately 
suggest the need for additional intervention, or if additional data are 
presented that would justify revising any requirements of this AD, the 
FAA may consider further rulemaking on this issue. In consideration of 
the amount of time that has already elapsed since issuance of the 
original notice of proposed rulemaking, the FAA has determined that 
further delay of this final rule action is not appropriate.

Request To Remove Landing Flap Limitation

    Two operators request removal of the landing flap limitation 
specified in paragraph (d) of the proposed AD. To justify the request, 
the commenters state that the difference in the approach speeds between 
the 30-degree and 40-degree landing flap configurations is only 5 
knots, and the proposed limitation would provide only minimal 
improvement in glideslope beam tracking.

[[Page 34782]]

    The FAA is aware of the small difference in approach speeds and 
agrees with the request to remove the landing flap limitation. In the 
preamble of the proposed AD, the FAA indicated that additional studies 
were being conducted to develop applicable operating limitations that 
would address approach flap settings. The FAA has since obtained 
additional analysis indicating that the new gain schedule applies to 
both 30-degree and 40-degree landing flap configurations. Therefore, 
paragraph (d) of the proposed AD has been removed from the final rule, 
and subsequent paragraphs have been reidentified.

Request To Revise Applicability: Exclude Certain Airplanes

    Two operators request that the applicability of the proposed AD be 
revised to exclude airplanes equipped with single-pitch channels that 
use radio altimeter-based glideslope gain programming. One commenter 
reports that most of the affected airplanes in its fleet have been 
modified to incorporate a dual-pitch computer configuration in 
accordance with Sperry Service Bulletin 21-1132-121, dated November 23, 
1982 (for SP-50 autopilots); or 21-1132-122, dated February 7, 1983 
(for SP-150 autopilots). (Those service bulletins were cited in the 
proposed AD as the appropriate source of service information for the 
one-time test of the modified autopilot.) This commenter adds that 
compliance with paragraphs (b) and (c) of the proposed AD would be 
impossible for those airplanes because the proposed AD and Boeing 
service bulletin are targeted for airplanes with single-channel 
autopilot systems. In addition, this commenter states that paragraph 
(a) of the proposed AD imposes an undesirable restriction on modified 
airplanes by preventing them from flying category II and category III 
approaches into airports with inoperative middle markers. This 
commenter asserts that this restriction is unnecessary for the modified 
airplanes because their autopilot configurations use radio altimeter 
glideslope gain programming (radio altitude-based desensitization), and 
are therefore not susceptible to the airworthiness concern associated 
with inoperative middle markers addressed by the proposed AD. The 
commenter recommends that the applicability of the proposed AD be 
revised to exclude those airplanes.
    The other commenter notes that affected airplanes with single-pitch 
channels on which the actions specified in Boeing Service Bulletin 727-
22-0052 have been incorporated do not use the middle marker in gain 
programming. The commenter concludes that these airplanes should not be 
prohibited from category II approaches if no middle marker is 
available.
    The FAA agrees. In this case, where the autopilot has already been 
modified with an FAA-approved design that does not normally use time-
based gain programming, the FAA agrees that excluding airplanes 
equipped with radio altimeter-based autopilots from the applicability 
of the AD will not compromise the safety of the fleet. The 
applicability of this AD has been revised accordingly.

Request To Revise Applicability: Clarify Intent

    Several commenters request that the applicability of the proposed 
AD be revised to clarify that the requirements apply only if operators 
desire to maintain the capability of the autopilot coupled ILS 
approach. One operator, conducting ``Cat I approach only,'' requests 
exclusion from the applicability of the AD.
    The FAA partially agrees. The intent of the AD is to ``prevent 
dangerous pitch oscillations during coupled (ILS) approaches''; 
affected operators could comply with the AD simply by never conducting 
coupled approaches. Although the cited wording does not directly 
address category I coupled approaches, analysis has shown that, if the 
unmodified autopilot is used, potentially unsafe pitch oscillation can 
begin at 400 feet above ground level (AGL), which is well above the 
typical decision height for category I approaches of 200 feet AGL. As a 
result, category I and category II coupled approaches would be 
prohibited for airplanes that have unmodified autopilot gains. However, 
manually flown approaches using autopilot guidance (glideslope and 
localizer needle deviations) or flight director guidance would be 
permitted. Because the middle marker signal is typically received at 
200 feet AGL and because during typical category I coupled approaches 
the pilot disconnects the autopilot at 200 feet AGL (compared to 100 
feet AGL, which is typical for category II approaches), no AFM 
restriction for category I approaches is discussed in the AD even 
though modification of the autopilot is required if it is used for any 
coupled approach. The AFM language has been further revised in 
paragraph (a) of this final rule to clarify that the autopilot must be 
modified if any coupled ILS approach is conducted. To more clearly 
identify those airplanes affected by this requirement, new paragraph 
(e) has been added to the final rule to require modification of the 
autopilot unit only if autopilot coupled ILS approaches are to be used 
with that airplane. Subsequent paragraphs that appeared in the proposed 
AD have been reidentified in the final rule.

Request To Revise Applicability: Add Certain Airplanes

    The applicability of the proposed AD includes only those Model 727-
100 and -200 series airplanes that are listed in Boeing Alert Service 
Bulletin 727-22A0093, dated December 20, 2000. One operator reports 
that some of its airplanes are not listed in the service bulletin but 
are equipped with SP-50 and/or SP-150 autopilots. The FAA infers that 
the commenter is requesting that the applicability of the proposed AD 
be expanded to include any Model 727-100 and -200 series airplane 
equipped with a subject autopilot.
    The FAA does not agree. Not all Model 727-100 or -200 series 
airplanes with the subject autopilots are susceptible to the unsafe 
condition identified by this AD. For example, airplanes delivered after 
November 1977 are not susceptible because they use radio altimeter gain 
scheduling for the SP-150 autopilots instead of the time-based gain 
scheduling discussed in the proposed AD. No change to the applicability 
of the final rule is necessary in this regard.

Request for Clarification of Test

    Two commenters request clarification of the one-time test specified 
by paragraph (c) of the proposed AD. The commenters state that this 
requirement, as written, is either redundant or subject to 
misinterpretation. The Sperry service bulletins, described previously, 
were cited in the proposed AD: in paragraph (c) for the one-time test 
procedures and in paragraph (d) for the autopilot modification 
procedures. (Paragraph (d) has since been removed from the final rule, 
as discussed previously.) The proposed AD specified that the test be 
done concurrently with the modification, before reinstallation of the 
modified autopilot, and before further flight. The commenters suggest 
that the wording of the proposed AD could cause operators to perform 
unnecessary rework. The commenters suggest that the proposed test 
requirement be a one-time test of the autopilot unit, because ``the 
timing in relation to the modification is immaterial.''
    One operator requests that the proposed test requirement be revised 
to distinguish the requirements associated with the autopilot from 
those associated with the airplane. This commenter suggests that 
paragraph (c) of the

[[Page 34783]]

proposed AD be revised to read as follows: ``Following any * * * 
modification, perform a one-time test procedure of the modified 
autopilot.'' The wording in the proposed AD suggests that two tests are 
to be done at the same time. The commenter requests this change to 
clarify the requirements and to avoid unnecessary rework.
    The FAA partially agrees. The requirements regarding the autopilot 
test may be redundant because the Sperry service bulletins already 
specify testing the unit using test information provided in those 
service bulletins. However, those same service bulletins note that, 
``Test information given in this bulletin shall be disregarded when 
revised Component Maintenance Manuals become available.'' This note may 
be misinterpreted to mean the test is not required, so the FAA finds it 
necessary to clarify the test requirement. The FAA has learned that 
many operators have already accomplished the modifications and post-
modification testing specified in the proposed AD. Therefore, paragraph 
(c) of the final rule has been revised to clarify this requirement.

Request To Allow Alternative Testing Methods

    One operator asserts that a variety of effective methods have been 
used to verify the new time constants described in the Sperry service 
bulletins for the test. The commenter suggests that the methods of 
compliance for paragraph (c) of the proposed AD be broadened to allow 
the option of ``other valid methods.'' The commenter reports that some 
of its autopilot units were modified and tested in-house in accordance 
with established test procedures described in the component maintenance 
manual. The commenter adds that other autopilot units were purchased 
already modified in accordance with the procedures described in the 
Sperry service bulletins. The commenter suggests this change to avoid 
unnecessary retesting of autopilot units for which the use of the new 
time constants has already been confirmed.
    The FAA agrees with the request for the reasons stated by the 
commenter. Paragraph (c) of the final rule has been further revised to 
provide operators this testing option.

Request To Revise Requirements for Spare Parts

    One operator requests that paragraph (e) of the proposed AD be 
either removed from the AD or revised to extend the time allowed for 
spares modifications and AFM revisions. This commenter asserts that a 
minimum of 6 months will be necessary to modify spare parts and revise 
the AFM.
    The FAA partially agrees. The FAA finds that the AFM limitations 
imposed by this AD will sufficiently ensure safety of an affected 
airplane until spare parts can be acquired and modified; therefore, 
allowing additional time to modify spare parts will not compromise 
safety. However, the FAA does not agree that it is necessary to extend 
the time by which the AFM revisions must be completed. The basic intent 
of an AFM revision may be accomplished by inserting a copy of the AD 
into the AFM; operators should be able to complete this action in a 
short time. Paragraph (f) of the final rule (paragraph (e) in the 
proposed AD) has been revised to extend the time by which the 
installation of unmodified spare parts will be prohibited.

Request To Revise Cost Estimate

    Two operators request a revision of the proposed cost estimates. 
One operator notes that the proposed AD does not address the costs 
associated with obtaining a master change from Boeing to eliminate the 
need for a middle marker to begin second-stage gain programming. One 
operator notes that the proposed AD does not address the costs 
associated with airplane diversions that would result if category II 
approaches are prohibited at airports without middle markers.
    The FAA partially agrees. Since category II approaches are 
prohibited at airports that do not have middle markers, an operator may 
elect to fly category I or manual approaches, divert to another 
airport, or modify the autopilot to operate with radio-altimeter-based 
gain schedule with control law that does not depend on the middle 
marker signal. However, the middle marker signal has always been and 
remains a necessary part of the autopilot that is programmed with a 
time-based gain schedule. This AD in part is intended to ensure the 
safe operation of an airplane--within the original autopilot design 
constraints associated with use of middle markers--by way of 
operational requirements. No change to the final rule is necessary in 
this regard.

Request To Revise Parts Cost Estimate

    One operator asserts that the parts cost to modify each SP-150 
autopilot is $641--not $168 as stated in the proposed AD.
    According to updated information provided by Boeing to the FAA, the 
parts cost is $522 for the SP-50 autopilot and $620 for the SP-150 
autopilot. The Cost Impact section of the final rule has been revised 
accordingly.

Request To Reactivate Middle Markers

    The proposed AFM revision requirement would prohibit a category II 
autopilot coupled ILS approach when the middle marker is inoperative. 
One operator suggests that the FAA reactivate middle markers as an 
alternative to the AFM revision requirement. The commenter claims that 
the FAA has deactivated ground-based middle marker beacons, and some 
operators have maintained their airborne marker beacon systems.
    The FAA does not agree with the request. The use of the middle 
marker is an original design feature of the subject autopilots. If the 
middle marker is inoperative or nonexistent, these autopilots--which 
are time-based--will not work properly. The FAA has approved autopilots 
that do not rely on marker beacons. Furthermore, the FAA currently is 
not considering reactivating the marker beacon system due to the 
International Civil Aviation Organization's September 1984 revision to 
Annex 10, which expanded the use of ILS/distance measuring equipment 
(DME) as a substitute for all or part of the marker beacon system. No 
change to the final rule is necessary in this regard.

Request To Revise Cause of Unsafe Condition

    Boeing requests a change to the second sentence of the Discussion 
section of the proposed AD. Specifically, this commenter requests that 
the revised sentence read as follows: ``The approach was normal until 
the airplane passed through 200 feet above ground level, where the 
airplane, responding to a [glideslope] beam anomaly, started a pitch 
oscillation that continued to increase.'' The FAA infers that the 
commenter is suggesting that the glideslope beam anomaly contributes to 
the pitch oscillation problem.
    The FAA does not agree with the request, but agrees that the 
glideslope beam anomaly can contribute to the pitch oscillation 
problem, and may have been a contributing factor to the accident 
described in the proposed AD. However, there were no indications that a 
glideslope anomaly contributed directly to the accident. Numerous 
runway 14R records dating from a time prior to the accident indicate no 
glideslope deviations or other ILS-related problems. The results of 
normal and special flight checks of the ILS were also within normal 
limits. Furthermore, results of simulator testing using typical 
glideslope profiles have indicated that

[[Page 34784]]

the autopilot with the 150-second desensitization period responded to 
the disturbances (induced turbulence and vertical wind gusts) by 
commanding oscillatory pitch changes or changes in pitch that are 
oscillatory in nature, which increased over time and resulted in 
significant deviations from the desired flight path. No change to the 
final rule is necessary in this regard.

Request To Expand AFM Requirements

    Boeing suggests that the proposed AFM revisions include additional 
indicators for approach performance, such as flightcrew monitoring for 
allowable ILS deviations and horizontal stabilizer activity that 
indicate an out-of-trim nonstabilized approach. The commenter provides 
no justification for this request.
    In consideration of the amount of time that has already elapsed 
since the issuance of the original notice, the FAA has determined that 
further delay of this final rule is not appropriate. However, if 
additional data are presented that would justify revising the 
requirements of this AD, the FAA may consider further rulemaking to 
require AFM revisions that would include the specific requested 
performance indicators. No change to the final rule is necessary in 
this regard.

Request To Revise Special Flight Permit Specifications

    Boeing requests that, instead of issuing a special flight permit to 
allow operation of the airplane to a location where the requirements of 
the AD can be accomplished, the FAA impose operational restrictions on 
autopilot coupled ILS approaches for that flight.
    The FAA partially concurs. The FAA finds that such operational 
restrictions are acceptable but not necessary in this case because 
another method is available to operate the airplane; i.e., the airplane 
can be manually operated during approaches. No change to the final rule 
regarding this issue is necessary.

Request To Clarify Airplanes Affected by Certain Requirements

    One operator requests that paragraph (e) (``Spare Parts'') of the 
proposed AD be revised to more clearly identify those airplanes that 
would be affected by that proposed requirement. The commenter suggests 
that the term ``any airplane,'' as it is used in that paragraph, be 
clarified to explain that not all Model 727-100 and -200 series 
airplanes are subject to this requirement.
    The FAA agrees that not all existing Model 727-100 and -200 series 
airplanes are subject to the identified unsafe condition; however, the 
FAA does not agree that revision of this paragraph is necessary. As 
stated earlier, the applicability of the final rule has been revised to 
exclude airplanes equipped with radio altimeter-based autopilots. Any 
qualifier (including ``any'' and ``all'') used to identify airplanes 
subject to a particular requirement of an AD is relative to the overall 
applicability of the AD.

Request To Revise Description of the Unsafe Condition

    Boeing requests a revision of one sentence in the third paragraph 
of the Discussion section of the proposed AD. That sentence reads as 
follows:

    Because glideslope deviations close to the runway require 
smaller pitch corrections than those required far from the runway, 
the autopilot sensitivity has to be reduced as the airplane nears 
the runway.

The commenter requests that the sentence be replaced with the 
following:

    The autopilot sensitivity has to be reduced as the airplane 
nears the runway because the glideslope beam converges as the 
distance to the glideslope transmitter is decreased (and the same 
vertical displacement from the beam centerline results in a larger 
glideslope deviation signal).

This commenter provides no justification for this requested change.
    The FAA does not agree with this request. Although the requested 
language is technically correct, the FAA finds that the simpler 
explanation in the Discussion section of the proposed AD is adequate to 
explain the conditions that require autopilot sensitivity changes. No 
change to the final rule is necessary in this regard.

Request To Revise Description of Accident Cause

    Boeing requests a change to one sentence of the final paragraph of 
the Discussion section of the proposed AD. That sentence reads as 
follows:

    Based on the NTSB's studies and FAA findings, the improper 
desensitization schedule is considered a contributing factor in the 
destabilized approach of the accident flight and in the reported 
pitch event that occurred in 1997.

This commenter requests that the word ``improper'' be changed to ``150-
second.''
    The FAA partially concurs. The requested wording is specific; 
however, the Discussion section is not repeated in a final rule, so no 
change is necessary in this regard.

Explanation of Additional Changes to AFM

    Some minor additional changes have been made to paragraph (a) of 
this final rule. First, the prohibition of coupled ILS approaches, 
specified in the proposed AD only for ``inoperative'' middle markers, 
has been changed in this final rule to ``inoperative or nonexistent'' 
middle markers. Second, the second sentence of the revised AFM language 
has been changed from ``* * * during Cat II autopilot coupled ILS 
approaches'' to ``* * * during coupled ILS CAT II approaches.''

Conclusion

    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 previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Cost Impact

    There are approximately 750 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 162 airplanes of U.S. registry 
will be affected by this AD.
    It will take approximately 1 work hour per airplane to revise the 
AFM, at an average labor rate of $60 per work hour. Based on this 
figure, the cost impact of the required AFM revisions on U.S. operators 
is estimated to be $9,720, or $60 per airplane.
    It will take approximately 1 work hour per airplane to modify and 
test the SP-50 autopilot and 2 work hours per airplane to modify and 
test the SP-150 autopilot. Required parts will cost approximately $522 
for the SP-50 autopilot and $620 for the SP-150 autopilot. Based on 
these figures, the cost impact of the modification and test is 
estimated to be $582 (SP-50) or $740 (SP-150) per airplane.
    The overall cost to the affected fleet could range from $104,004 to 
$301,320.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the requirements of this 
AD action, and that no operator would accomplish those actions in the 
future if this AD were not adopted. The cost impact figures discussed 
in AD rulemaking actions represent only the time necessary to perform 
the specific actions actually required by the AD. These figures 
typically do not include incidental costs, such as the time required to 
gain access and close up, planning time, or time necessitated by other 
administrative actions.

[[Page 34785]]

Regulatory Impact

    The regulations adopted herein will 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. Therefore, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    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 
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

0
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

0
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]

0
2. Section 39.13 is amended by adding the following new airworthiness 
directive:

2003-11-19 Boeing: Amendment 39-13178. Docket 2001-NM-41-AD.

    Applicability: Model 727-100 and 727-200 series airplanes, 
certificated in any category, as listed in Boeing Alert Service 
Bulletin 727-22A0093, dated December 20, 2000; excluding airplanes 
equipped with radio altimeter-based autopilots.

    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) 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 undesirable and potentially dangerous pitch 
oscillations during coupled instrument landing system (ILS) 
approaches, accomplish the following:

Revision of Airplane Flight Manual (AFM)

    (a) For any airplane on which autopilot coupled ILS approaches 
with time-based glideslope gain programming are used: Within 6 
months after the effective date of this AD, revise the Limitations 
Section, under AUTOPILOT/FLIGHT DIRECTOR SYSTEM, of the FAA-approved 
AFM by adding the following (this may be accomplished by inserting a 
copy of this AD into the AFM):

    ``Coupled ILS approaches are prohibited unless the autopilot has 
been modified in accordance with AD 2003-11-19, amendment 39-13178.
    CAT II autopilot coupled ILS approach shall not be performed if 
the Middle Marker (ground or airborne system) is inoperative or 
nonexistent.
    Disconnect the autopilot at, or prior to, 80 ft. (above the 
runway's touchdown-zone elevation) during coupled ILS CAT II 
approaches.''

Modification and Testing of Autopilot

    (b) Except as provided by paragraph (d) of this AD: Within 18 
months after the effective date of this AD, modify the existing SP-
50 or SP-150 single-channel autopilot in accordance with Boeing 
Alert Service Bulletin 727-22A0093, dated December 20, 2000.
    (c) Except as provided by paragraphs (d) and (e) of this AD: 
After modification of the autopilot unit required by paragraph (b) 
of this AD, and before reinstallation of the modified autopilot and 
further flight, perform a one-time test procedure of the modified 
autopilot, in accordance with Sperry Service Bulletin 21-1132-121, 
dated November 23, 1982 (for SP-50 autopilots); or 21-1132-122, 
dated February 7, 1983 (for SP-150 autopilots); as applicable. 
Testing done before the effective date of this AD in accordance with 
Component Maintenance Manual (CMM) test procedures is also 
acceptable, provided that the procedures implement all the CMM 
changes and test steps described in the applicable Sperry service 
bulletin. For autopilot units manufactured with the actions of the 
applicable Sperry service bulletin already incorporated, testing is 
not required.

Exempt Conditions

    (d) For airplanes with autopilots already modified prior to the 
effective date of this AD in accordance with Sperry Service Bulletin 
21-1132-121 or 21-1132-122: Only the AFM limitation specified in 
paragraph (a) of this AD is required.
    (e) For any airplane on which coupled approaches are not used: 
Only the AFM limitation specified in paragraph (a) of this AD is 
required, provided a flight deck placard is installed that states, 
``Autopilot coupled ILS approach prohibited'' or equivalent, in 
accordance with a method approved by the Manager, Seattle Aircraft 
Certification Office (ACO), FAA. For a repair method to be approved 
by the Manager, Seattle ACO, as required by this paragraph, the 
Manager's approval letter must specifically reference this AD. 
However, for any airplane placed into service that uses autopilot 
coupled ILS approaches, the requirements of this AD must be 
accomplished before the first flight when a coupled approach is 
used.

Part Installation

    (f) As of 6 months after the effective date of this AD, no 
person may install on any airplane an autopilot pitch control 
computer unless it has been modified in accordance with this AD.

Alternative Methods of Compliance

    (g) 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 ACO, FAA. Operators shall 
submit their requests through an appropriate FAA Principal 
Operations or 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.

Special Flight Permits

    (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.

Incorporation by Reference

    (i) Unless otherwise specified in this AD, the actions must be 
done in accordance with Boeing Alert Service Bulletin 727-22A0093, 
dated December 20, 2000; Sperry Service Bulletin 21-1132-121, dated 
November 23, 1982; and Sperry Service Bulletin 21-1132-122, dated 
February 7, 1983; as applicable. Only the first page of Sperry 
Service Bulletins 21-1132-121 and 21-1132-122 contain the document 
number; no other page of the documents contain this information. 
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 Boeing Commercial Airplane Group, PO 
Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at 
the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., 
Renton, Washington; or at the Office of the Federal Register, 800 
North Capitol Street, NW., suite 700, Washington, DC.

Effective Date

    (j) This amendment becomes effective on July 16, 2003.


[[Page 34786]]


    Issued in Renton, Washington, on May 28, 2003.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 03-13976 Filed 6-10-03; 8:45 am]
BILLING CODE 4910-13-P