[Federal Register Volume 60, Number 124 (Wednesday, June 28, 1995)]
[Proposed Rules]
[Pages 33372-33374]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-15851]



      
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DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 95-NM-22-AD]


Airworthiness Directives; Boeing Model 747-100, -200, -300, and 
SP Series Airplanes

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 747-100, -
200, -300, and SP series airplanes. This proposal would require 
revising the Airplane Flight Manual (AFM) to prohibit the use of the 
autoland function. This proposed AD would also require installation of 
a diode and a marker on shelves, making wiring changes to the flight 
mode annunciator (FMA) of the autopilot/flight director system, which 
would terminate the requirements for the AFM revision; and follow-on 
operational tests. This proposal is prompted by a report indicating 
that, during a triple channel approach, the autoland system failed to 
flare a Model 747-200 series airplane for landing, which resulted in a 
hard landing. The actions specified by the proposed AD are intended to 
prevent failure of the autoland system to flare the airplane for 
landing, which could subsequently result in a hard landing.

DATES: Comments must be received by August 22, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-NM-22-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: Hania Younis, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Transport Airplane 
Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, 
SW., Renton, Washington 98055-4056; telephone (206) 227-2764; fax (206) 
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 95-NM-22-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-103, Attention: Rules 
Docket No. 95-NM-22-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received a report indicating that, during a triple 
channel approach, the autoland system failed to flare a Boeing Model 
747-200 series airplane for landing, which resulted in a hard landing. 
Investigation revealed that the approach was initiated with an 
inoperative number 3 NAV receiver (thereby making the channel ``C'' 
autopilot inoperative). Investigation also revealed that a separate 
failure caused the channel ``B'' autopilot to automatically disengage 
at the start of the flare. This resulted in loss of the autopilot 
function due to the disagreement between channel ``A'' and channel 
``C.''
    The integrity of the autoland system depends on a fault annunciator 
system. An invalid discrete signal from the number 3 NAV receiver 
should cause the glideslope (G/S) flag located on the P2 panel to 
illuminate. Along with this G/S flag on the P2 panel, the channel ``C'' 
autopilot system should have annunciated a steady amber autopilot 
warning light on the captain's and first officer's flight mode 
annunciator (FMA). This warning light would alert the flightcrew that 
the autopilot had changed from fail-operational to fail-passive mode. 
The subsequent dual channel autopilot failure should have been 
annunciated by a steady red warning light, warning the flightcrew that 
the autopilot had changed from fail-passive mode to complete autopilot 
disconnect.
    Further investigation revealed that the autopilot warning light on 
the captain's and first officer's FMA did not illuminate during this 
dual channel fault incident. The cause of this lack of annunciation has 
been attributed to the faulty logic of the autopilot/flight director 
system.
    This condition, if not corrected, could result in failure of the 
autoland system to flare the airplane for landing, which may result in 
a hard landing.
    The FAA has reviewed and approved Boeing Alert Service Bulletin 
747-22A2212, Revision 1, dated April 27, 1995, and Boeing Alert Service 
Bulletin 747-22A2213, Revision 1, dated April 27, 1995, which describe 
procedures for installing a diode and a marker on the E1-4, E1-5, and 
E1-6 shelves, and making wiring changes to the FMA of the autopilot/
flight director system. These service bulletins also describe 
procedures for performing operational tests of the newly installed 
diodes. This installation and wiring change will ensure the 
illumination of a steady amber autopilot warning light on the captain's 
and the first officer's FMA's when a sensor fails after commencement of 
a triple autopilot approach.
    The autopilot/flight director system installed on Boeing Model 747-
200 series airplanes is similar in design to the autopilot/flight 
director system installed on Model 747-100, -300, and SP series 
airplanes; therefore, the FAA finds that Model 747-100, -300, and SP 
series airplanes are subject to the same unsafe condition identified in 
this proposal.
    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 revising the Limitations Section of the FAA-
approved Airplane Flight Manual (AFM) to prohibit the use of the LAND 
mode, if there is a flag on any channel. This proposed AD would also 
require installing a diode and a marker on certain shelves, and making 
wiring [[Page 33374]] changes to the FMA of the autopilot/flight 
director system, which would terminate the requirement for an AFM 
revision. Additionally, this proposed AD requires operational tests of 
the newly installed diodes. The installation, wiring changes, and 
operational tests would be required to be accomplished in accordance 
with the alert service bulletins described previously.
    As a result of recent communications with the Air Transport 
Association (ATA) of America, the FAA has learned that, in general, 
some operators may misunderstand the legal effect of AD's on airplanes 
that are identified in the applicability provision of the AD, but that 
have been altered or repaired in the area addressed by the AD. The FAA 
points out that all airplanes identified in the applicability provision 
of an AD are legally subject to the AD. If an airplane has been altered 
or repaired in the affected area in such a way as to affect compliance 
with the AD, the owner or operator is required to obtain FAA approval 
for an alternative method of compliance with the AD, in accordance with 
the paragraph of each AD that provides for such approvals. A note has 
been included in this notice to clarify this long-standing requirement.
    There are approximately 172 Model 747-100, -200, -300, and SP 
series airplanes of the affected design in the worldwide fleet. The FAA 
estimates that 11 airplanes of U.S. registry would be affected by this 
proposed AD, that it would take approximately 11 work hours per 
airplane to accomplish the proposed actions, and that the average labor 
rate is $60 per work hour. Required parts would cost approximately $613 
per airplane. Based on these figures, the total cost impact of the 
proposed AD on U.S. operators is estimated to be $14,003, or $1,273 per 
airplane.
    The total cost impact figure discussed above is 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.
    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. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

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

Boeing: Docket 95-NM-22-AD.

    Applicability: Model 747-100, -200, -300, and SP series 
airplanes, equipped with triple channel autoland autopilots; as 
listed in Boeing Alert Service Bulletin 747-22A2212, Revision 1, 
dated April 27, 1995, and Boeing Alert Service Bulletin 747-22A2213, 
Revision 1, dated April 27, 1995; 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 use the authority 
provided in paragraph (d) of this AD to request approval from the 
FAA. This approval may address either no action, if the current 
configuration eliminates the unsafe condition; or different actions 
necessary to address the unsafe condition described in this AD. Such 
a request should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any airplane from the applicability of this AD.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of the autoland system to flare the airplane 
for landing, which may result in a hard landing, accomplish the 
following:
    (a) Within 3 months after the effective date of this AD, revise 
the Limitations Section of the FAA-approved Airplane Flight Manual 
(AFM) to include the following statement. This may be accomplished 
by inserting a copy of this AD in the AFM.
    ``Pay close attention to all 3 NAV receiver flags after FLARE 
ARM is annunciated on the FMA's. If there is a flag on ANY channel, 
the approach must be down-graded to dual channel, CAT II 
configuration, and the autopilot must be disconnected prior to 
landing.''
    (b) Within 18 months after the effective date of this AD, 
install a diode and a marker on the E1-4, E1-5, and E1-6 shelves, 
and make wiring changes to the flight mode annunciator of the 
autopilot/flight director system, in accordance with Boeing Alert 
Service Bulletin 747-22A2212, Revision 1, dated April 27, 1995, or 
Boeing Alert Service Bulletin 747-22A2213, Revision 1, dated April 
27, 1995; as applicable. After this installation and wiring change 
is accomplished, the AFM revision required by paragraph (a) of this 
AD may be removed from the AFM.
    (c) Prior to further flight after accomplishment of paragraph 
(b) of this AD, perform an operational test of the newly installed 
diodes, in accordance with Boeing Alert Service Bulletin 747-
22A2212, Revision 1, dated April 27, 1995, or Boeing Alert Service 
Bulletin 747-22A2213, Revision 1, dated April 27, 1995; as 
applicable. Thereafter, repeat the operational test at intervals not 
to exceed 20,000 flight hours.
    (d) 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.

    (e) Special flight permits may be issued in accordance with 
Secs. 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 June 22, 1995.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-15851 Filed 6-27-95; 8:45 am]
BILLING CODE 4910-13-U