[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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