[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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[[Page 33373]]
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
