[Federal Register Volume 61, Number 94 (Tuesday, May 14, 1996)]
[Rules and Regulations]
[Pages 24214-24216]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-11823]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-NM-127-AD; Amendment 39-9614; AD 92-10-13 R1]
RIN 2120-AA64
Airworthiness Directives; McDonnell Douglas Model DC-9-80 Series
Airplanes and Model MD-88 Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment revises an existing airworthiness directive
(AD), applicable to certain McDonnell Douglas Model DC-9-80 series
airplanes and Model MD-88 airplanes, that currently requires a revision
to the FAA-approved Airplane Flight Manual (AFM) to specify that the
autothrottles must be disconnected if engine surge (stall) is detected
during takeoff. That AD was prompted by results of an accident
investigation, which revealed that the digital flight guidance computer
(DFGC) on these airplanes can incorrectly identify an engine surge or
stall as being an engine failure. This can cause the autothrottles to
unclamp and automatically advance the thrust levers during takeoff. The
actions specified by that AD are intended to prevent automatic advance
of the thrust lever on a surging engine during takeoff, which could
cause engine failure. This amendment provides for an optional
terminating action for the AFM revision.
DATES: Effective June 13, 1996.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of June 13, 1996.
ADDRESSES: The service information referenced in this AD may be
obtained from McDonnell Douglas Corporation, 3855 Lakewood Boulevard,
Long Beach, California 90846, Attention: Technical Publications
Business Administration, Department C1-L51 (2-60). 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 FAA, Transport Airplane Directorate, Los Angeles
Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood,
California; or at the Office of the Federal Register, 800 North Capitol
Street, NW., suite 700, Washington, DC.
FOR FURTHER INFORMATION CONTACT: Robert Baitoo, Aerospace Engineer,
Propulsion Branch, ANM-140L, FAA, Transport Airplane Directorate, Los
Angeles Aircraft Certification Office, 3960 Paramount Boulevard,
Lakewood,
[[Page 24215]]
California; telephone (310) 627-5245; fax (310) 627-5210.
SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal
Aviation Regulations (14 CFR part 39) by superseding AD 92-10-13,
amendment 39-8247 (57 FR 19249, May 5, 1992), which is applicable to
certain McDonnell Douglas Model DC-9-80 series airplanes and Model MD-
88 airplanes, was published in the Federal Register on October 18, 1995
(60 FR 53888). That action proposed to require the installation of a
modified digital flight guidance computer (DFGC), which, when
accomplished, would terminate the requirement for the AFM revision.
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 Proposal
Three commenters support the proposed rule.
Requests To Withdraw the Proposal
Several commenters request that the FAA withdraw the proposed rule
or retain the proposed installation as an optional terminating action
for the AFM revision. The commenters contend that the requirements of
the proposed AD provide no additional safety over existing AD 92-10-13;
the safety of the affected airplanes is ensured by the currently
installed hardware and the procedural changes that are required by the
existing AD. One commenter, Honeywell, states that both AD 92-10-13 and
the proposed AD achieve the same goal of preventing forward throttle
movement in the event of an engine surge or stall. AD 92-10-13 achieves
this goal by requiring the pilot to recognize the surge condition and
to manually disconnect the autothrottles. The proposed AD accomplishes
this in a different manner--by forcing the DFGC autothrottles to remain
in the clamp mode. Because the engine surge condition is easily and
unambiguously recognized in the cockpit and the resultant action
required by AD 92-10-13 (disconnecting the autothrottle) is likewise
clear and easily accomplished, the correct execution for the subject
condition is assured. The commenters also state that accomplishment of
the requirements of the proposed AD would pose an immense cost to some
operators. The commenters contend that such expense is unnecessary when
an equivalent, alternative means is available.
The FAA does not concur with the requests to withdraw the final
rule. However, the FAA has determined that, based on the information
provided by the commenters, the currently installed hardware and the
procedural changes required by the existing AD do provide a long term
and adequate level of safety. While the manufacturer has advised the
FAA that the new DFGC (part number 4034241-972) was incorporated on all
production Model DC-9-80 series airplanes as of July 1995, the FAA has
determined that the installation should be provided in this AD as an
optional terminating action for the AFM revision. Therefore, this
action revises AD 92-10-13 to add a new paragraph (c) that provides for
installation of the new DFGC's as an optional terminating action for
the AFM revision.
Other Changes to the Final Rule
The FAA also has clarified the applicability of this rule to
specify that only airplanes equipped with digital flight guidance
computers (DFGC) having part numbers prior to 4034241-972 are subject
to the requirements of the AD. This change will exclude airplanes on
which the terminating installation has been accomplished previously or
in production.
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 1,117 McDonnell Douglas Model DC-9-80
series airplanes and Model MD-88 airplanes of the affected design in
the worldwide fleet. The FAA estimates that 643 airplanes of U.S.
registry will be affected by this AD.
The AFM revision that is currently required by AD 92-10-13 takes
approximately 1 work hour per airplane to accomplish, at an average
labor rate of $60 per work hour. Based on these figures, the cost
impact on U.S. operators of this current requirement is estimated to be
$38,580, or $60 per airplane.
The cost impact figure discussed above is 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.
Should an operator elect to accomplish the optional terminating
action that is provided by this AD action (the removal of DFGC's having
part number 4034241-971 and installation of DFGC's having part number
4034241-972), it would take approximately 1 work hour per airplane to
accomplish, at an average labor rate of $60 per work hour. Required
parts will cost approximately $2,000 per airplane (that is, $1,000 per
DFGC, and 2 DFGC's per airplane). Based on these figures, the cost
impact of the optional terminating action is estimated to be $2,060 per
airplane.
Should an operator have an airplane equipped with DFGC's having
part numbers other than (lower than) 4034241-971, additional actions
may be necessary prior to accomplishing the optional terminating
action. Those additional actions involve modification(s) of the DFGC's
to bring them to the level of configuration of DFGC's having part
number 4034241-971. Depending on the current configuration of the
DFGC's installed on the airplane, the highest costs associated with
modifying a DFGC to a part number 4034241-971 configuration (excluding
subsequent modification to the part number 4034241-972 configuration)
could be as much as $92,000 per airplane (that is, $46,000 per DFGC,
and 2 DFGC's per airplane).
Regulatory Impact
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
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.
[[Page 24216]]
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 removing amendment 39-8247 (57 FR
19249, May 5, 1992), and by adding a new airworthiness directive (AD),
amendment 39-9614, to read as follows:
92-10-13 R1 McDonnell Douglas: Amendment 39-9614. Docket 95-NM-127-
AD. Revises AD 92-10-13, Amendment 39-8247.
Applicability: Model DC-9-80 series airplanes and Model MD-88
airplanes equipped with digital flight guidance computers (DFGC)
having part numbers prior to 4034241-972; 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 request approval for an
alternative method of compliance in accordance with paragraph (d) 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 automatic thrust lever advance on a surging engine
during takeoff, which could cause engine failure, accomplish the
following:
(a) Within 30 days after May 20, 1992 (the effective date of AD
92-10-13, amendment 39-8247), 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.
``LIMITATIONS SECTION
Autothrottles must be disconnected if engine surge (stall) is
detected during takeoff.''
(b) Within 30 days after May 20, 1992 (the effective date of AD
92-10-13, amendment 39-8247), revise the Procedures Section of the
FAA-approved AFM to include the following statement. This may be
accomplished by inserting a copy of this AD in the AFM.
``PROCEDURES SECTION
CAUTION
During takeoff, the Digital Flight Guidance Computer (DFGC)
engine failure logic is armed if (1) the flight director pitch axis
is in takeoff mode, (2) the aircraft is above 400 feet radio
altitude, and (3) both engine pressure ratios (EPRs) are below the
go-around EPR limit. If the DFGC detects an EPR drop greater than or
equal to 0.25 EPR and 7% N1 from the same engine, as compared
to the other engine, the engine failure logic is satisfied and the
DFGC will change the Thrust Rating Panel (or indicator) thrust limit
to Go-Around (GA). This will cause the autothrottle system to
unclamp and enter normal EPR limit (EPR LIM) mode where the
throttles will maintain the higher engine EPR at the selected go-
around thrust rating EPR LIM. Such an EPR and N1 drop may also
result from an engine surge (stall). Advancing thrust levers on a
surging engine will hinder surge recovery and may result in eventual
engine failure.
If an engine surge (stall) is detected during takeoff:
(1) Disconnect autothrottles.
(2) Reduce thrust on affected engine (idle if necessary).
(3) Shut down the affected engine if surging and popping continues.
(4) If affected engine surging or popping stops, accomplish the
following:
A. Place ignition switch to GRD START & CONTIN.
B. Place ENG anti-ice switches to ON.
C. Place PNEU X-FEED VALVE lever OPEN on affected side.
D. Place AIR FOIL anti-ice switches ON.
E. Advance affected throttle slowly.
(5)- If engine surging or popping returns, turn the ENG anti-ice
switch OFF.
(6)- After normal operation has been established, the autothrottles
may be re-engaged.
Note: A NO MODE light may be annunciated due to abnormal bleed
configuration.''
(c) Replacement of both DFGC's having a part number prior to
4034241-972, with DFGC's having part number 4034241-972, in
accordance with McDonnell Douglas Service Bulletin MD80-22-111,
dated May 23, 1995, constitutes terminating action for the
requirements of this AD. Once the replacements are accomplished, the
AFM revisions required by paragraphs (a) and (b) of this AD may be
removed.
Note 2: McDonnell Douglas Service Bulletin MD80-22-111, dated
May 23, 1995, references Honeywell Service Bulletin 4034241-22-44,
dated May 22, 1995, as an additional source of service information.
Note 3: Paragraph 1.B of McDonnell Douglas Service Bulletin
MD80-22-111, dated May 23, 1995, specifies certain concurrent
actions that affect airplanes equipped with DFGC's having part
numbers prior to 4034241-971.
(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, Los Angeles 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, Los Angeles ACO.
Note 4: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Los Angeles ACO.
(e) 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.
(f) The replacement shall be done in accordance with McDonnell
Douglas Service Bulletin MD80-22-111, dated May 23, 1995. 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 McDonnell Douglas Corporation, 3855
Lakewood Boulevard, Long Beach, California 90846, Attention:
Technical Publications Business Administration, Department C1-L51
(2-60). Copies may be inspected at the FAA, Transport Airplane
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the
FAA, Los Angeles Aircraft Certification Office, Transport Airplane
Directorate, 3960 Paramount Boulevard, Lakewood, California; or at
the Office of the Federal Register, 800 North Capitol Street, NW.,
suite 700, Washington, DC.
(g) This amendment becomes effective on June 13, 1996.
Issued in Renton, Washington, on May 6, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-11823 Filed 5-13-96; 8:45 am]
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