[Federal Register Volume 59, Number 43 (Friday, March 4, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-4952]


[[Page Unknown]]

[Federal Register: March 4, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 92-NM-48-AD; Amendment 39-8593; AD 93-11-01]

 

Airworthiness Directives; McDonnell Douglas Model DC-9-10 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; correction.

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SUMMARY: This document corrects information in an existing 
airworthiness directive (AD) that is applicable to certain McDonnell 
Douglas Model DC-9-10 series airplanes. Among other things, the 
existing AD currently requires a modification of the wing leading edge 
bleed air anti-ice system so that it can operate on the ground to 
prevent ice reformation after deicing procedures have been 
accomplished, and a related revision to the Airplane Flight Manual 
(AFM). The actions specified in that AD are intended to prevent 
degradation of lift due to ice accumulation on the wing leading edge. 
This amendment corrects the instructional language in the required AFM 
revision related to operation of the system on the ground. This action 
is prompted by apparent confusion that this language has created among 
affected operators in attempting to comply with the rule.

DATES: Effective July 22, 1993. The incorporation by reference of 
certain publications listed in the regulations was previously approved 
by the Director of the Federal Register as of July 22, 1993 (58 FR 
33898, June 22, 1993).

ADDRESSES: The service information referenced in this AD may be 
obtained from McDonnell Douglas Corporation, P.O. Box 1771, Long Beach, 
California 90801-1771, Attention: Business Unit Manager, Technical 
Administrative Support, Dept. L51, Mail Code 2-98. 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, Los Angeles Aircraft Certification Office, 
3229 East Spring Street, Long Beach, California; or at the Office of 
the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.

FOR FURTHER INFORMATION CONTACT: Walter Eierman, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130L, FAA, Transport Airplane 
Directorate, Los Angeles Aircraft Certification Office, 3229 East 
Spring Street, Long Beach, California 90806-2425; telephone (310) 988-
5336; fax (310) 988-5210.

SUPPLEMENTARY INFORMATION: On May 26, 1993, the FAA issued AD 93-11-01, 
Amendment 39-8593 (58 FR 33898, June 22, 1993), that is applicable to 
certain McDonnell Douglas Model DC-9-10 series airplanes. That AD 
superseded an existing AD that had required a revision to the FAA-
approved Airplane Flight Manual (AFM) to specify that takeoff must not 
be initiated unless the flight crew verifies that a visual and physical 
check of the leading edge and upper wing surfaces have been 
accomplished and that the wing is clear of all ice, frost, and snow 
accumulation. AD 93-11-01 added a requirement to modify the wing 
leading edge bleed air anti-ice system so that it can operate on the 
ground to prevent ice from reforming after deicing procedures have been 
accomplished. The actions specified in that AD are intended to prevent 
degradation of lift due to ice accumulation on the wing leading edge.
    Recently, the FAA has become aware of the fact that certain 
language contained in the required AFM limitation, relative to 
operation of the wing leading edge bleed air anti-ice system, has 
created confusion among affected operators when attempting to comply 
with the rule.
    Specifically, paragraph (d)(2) of AD 93-11-01 requires that the 
Limitations Section of the AFM be revised to require that ``the bleed 
air anti-ice system must be on whenever conditions exist or are 
anticipated, including on-ground operation.'' This phrase apparently 
has been interpreted to mean that operators must have the system on 
during the brief period during takeoff from aircraft rotation to about 
100 feet above ground level where the extraction of engine bleed air 
for the anti-ice system penalizes second-segment climb performance. 
Such a performance penalty could be as much as 4,000 pounds, which is 
roughly equivalent to off-loading 20 passengers. One operator contends 
that a penalty of this magnitude cannot be absorbed by operators and 
makes operation of Model DC-9-10/-15 aircraft ``economically not 
viable.''
    The purpose of the required AFM limitation was meant to ensure that 
the anti-ice system modification is used to provide the on-ground 
protection for which it is intended; the manner in which the system is 
normally operated during flight was not meant to be changed. The FAA 
acknowledges that the language of the AFM limitation as it appears 
currently in the AD could be interpreted to apply to both the ground 
and flight phases of airplane operation. Since this clearly was not the 
FAA's intent, the FAA has determined that it is appropriate to take 
action to correct the wording of the AFM limitation in AD 93-11-01 to 
specify that the bleed air anti-ice system must be on whenever icing 
conditions exist or are apparent, when on the ground, until immediately 
prior to commencement of takeoff roll.
    This corrected wording will clearly indicate that the limitation 
applies only to operation of the system while the airplane is on the 
ground until prior to takeoff. The selection of the anti-ice system 
during takeoff has always been the pilot's decision, and the FAA 
intends that it continue to be so.
    Additionally, another item that appeared in the preamble to AD 93-
11-01 has apparently created some confusion. In that preamble, the FAA 
stated the following in its description of the unsafe condition:

    ``The FAA notes that the description of the addressed unsafe 
condition, as discussed in the proposal, implied that the condition 
is a result of icing effects on both the wing upper surface and the 
wing leading edge. That language was inaccurate; the unsafe 
condition is likely to occur as the result of icing effects on the 
wing leading edge, not the wing upper surface.''

    The FAA has reconsidered this statement and finds that, while the 
modification of the wing leading edge bleed air anti-ice system 
required by AD 93-11-01 is effective only on ice forming on the wing 
leading edge, it would be misleading to state the unsafe condition 
addressed by that AD results only from that phenomenon. The unsafe 
condition addressed is that which is caused by ice contamination on the 
wing leading edge and upper surface; this condition can result in the 
degradation of wing lift, and can result in the airplane stalling at 
lower than normal angles-of-attack during takeoff. Therefore, the FAA 
hereby clarifies this point by replacing the previously used language 
with the following:

    ``The modification to the wing leading edge bleed air de-icing 
system, which is required by this AD, prevents ice/frost/snow from 
reforming on the wing leading edge only, after the airplane has been 
deiced. The wing leading edge area is the most critical from a loss 
of lift standpoint. However, because contamination on the upper 
surface of the wing can also impact lift and stall speeds, assurance 
that ice/frost/snow is not present on the wing leading edge and 
upper surface requires operation in accordance with the 
comprehensive requirements of Section 121.629(c) (Amendment 121-231) 
of the Federal Aviation Regulations (FAR), or the accomplishment of 
visual and physical (hands-on) inspections of both the leading edge 
and the wing upper surface as required by this AD.''

    Additionally, the address for obtaining copies of the referenced 
service material from the McDonnell Douglas Corporation has been 
corrected.
    Action is taken herein to correct these errors and to correctly add 
the AD as an amendment to Sec. 39.13 of the FAR (14 CFR part 39). The 
effective date of the rule remains July 22, 1993.
    The final rule is being reprinted in its entirety for the 
convenience of affected operators.
    Since this action only corrects wording in an existing rule, it has 
no adverse economic impact and imposes no additional burden on any 
person. Therefore, notice and public procedures hereon are unnecessary.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety. Adoption of the Correction.
    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 14 CFR part 
39 of the Federal Aviation Regulations 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 correctly adding the following 
airworthiness directive (AD):

93-11-01 McDonnell Douglas: Amendment 39-8593. Docket 92-NM-48-AD. 
Supersedes AD 92-03-01, Amendment 39-8155.

    Applicability: Model DC-9-11, -12, -13, -14, -15, and -15F 
series airplanes, certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent degradation of lift due to ice accumulation on the 
wing leading edge, accomplish the following:
    (a) Except as provided by paragraph (b) of this AD, within 10 
days after January 17, 1992 (the effective date of AD 92-03-01, 
Amendment 39-8155), revise the Limitations Section of the FAA-
approved Airplane Flight Manual (AFM) to include the following. This 
may be accomplished by inserting a copy of this AD in the AFM.

``Wing De-icing Prior to Takeoff

Caution

    The Model DC-9-10 series airplane has a wing design with no 
leading edge high lift devices, such as slats. Wings without leading 
edge devices are particularly susceptible to loss of lift due to 
wing icing. Minute amounts of ice or other contamination (equivalent 
to medium grit sandpaper) on the leading edges or wing upper 
surfaces can cause a significant reduction in the stall angle-of-
attack. This can increase the stall speed up to 30 knots. The 
increased stall speed can be well above the stall warning (stick 
shaker) activation speed.

[End of Cautionary Note]

    The leading edge and upper wing surfaces must be physically 
checked for ice/frost when the airplane has been exposed to 
conditions conducive to ice/frost formation. Takeoff may not be 
initiated unless the flight crew verifies that a visual check and a 
physical (hands-on) check of the leading edge and upper wing 
surfaces have been accomplished, and that the wing is clear of ice/
frost/snow accumulation. Icing/frost/snow conditions exist when the 
Outside Air Temperature (OAT) is below 6 degrees C (42 degrees F); 
and either the difference between the dew point temperature and OAT 
is less than 3 degrees C (5 degrees F), or visible moisture (rain, 
drizzle, sleet, snow, fog, etc.) is present.

Note

    This limitation does not relieve the requirement that aircraft 
surfaces are free of ice, frost, and snow accumulation as required 
by Federal Aviation Regulations Sections 91.527 and 121.629.

[End of Note]''

    (b) Paragraph (a) of this AD does not apply to any airplane that 
is both operated in accordance with Federal Aviation Regulation 
(FAR) 121.629(c), Amendment 121-231, and modified in accordance with 
either paragraph (c)(1) or (c)(2) of this AD.
    (c) Within 9 months after the effective date of this amendment, 
accomplish the procedures specified in either paragraph (c)(1) or 
(c)(2) of this AD:
    (1) Modify the bleed air anti-ice system so that it can operate 
on the ground to prevent ice reformation on the wing leading edges 
after ground equipment has been utilized to properly deice the 
airplane, and to minimize the effect of undetected ice/frost/snow 
contamination. Accomplish the modification in accordance with a 
method approved by the Manager, Los Angeles Aircraft Certification 
Office (ACO), FAA, Transport Airplane Directorate. Or
    (2) Install a supplemental on-ground wing leading edge ice 
protection system in accordance with McDonnell Douglas DC-9 Service 
Bulletin 30-65, dated October 8, 1992.
    (d) Upon the accomplishment of the modification required by 
paragraph (c) of this AD, revise the AFM in accordance with either 
paragraph (d)(1) or (d)(2) of this AD:
    (1) Revise the Limitations section to include appropriate 
operating procedures relative to operation of the modification 
required by paragraph (c) of this AD. These operating procedures 
must be approved by the Manager, Los Angeles Aircraft Certification 
Office (ACO), FAA, Transport Airplane Directorate. Or
    (2) Revise the Limitations section to include the following 
operating procedures relative to the operation of the modification 
required by paragraph (c) of this AD. This may be accomplished by 
inserting a copy of this AD in the AFM.

``Use of Bleed Air Anti-Ice System

Caution

    The Model DC-9-10 series airplane has a wing design with no 
leading edge high lift devices, such as slats. Wings without leading 
edge devices are particularly susceptible to loss of lift due to 
wing icing. Minute amounts of ice or other contamination (equivalent 
to medium grit sandpaper) on the leading edges or wing upper 
surfaces can cause a significant reduction in the stall angle-of-
attack. This can increase the stall speed up to 30 knots. The 
increased stall speed can be well above the stall warning (stick 
shaker) activation speed.

[End Of Cautionary Note]

    The bleed air anti-ice system must be on whenever icing 
conditions exist or are anticipated, when on the ground, until 
immediately prior to commencement of takeoff roll.''
    (e) 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: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles ACO.

    (f) Special flight permits may be issued in accordance with FAR 
21.197 and 21.199 to operate the airplane to a location where the 
requirements of this AD can be accomplished.
    (g) The installation of a supplemental on-ground wing leading 
edge ice protection system shall be done in accordance with 
McDonnell Douglas DC-9 Service Bulletin 30-65, dated October 8, 
1992. 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, as of July 22, 1993 (58 FR 33898, June 22, 1993). Copies 
may be obtained from McDonnell Douglas Corporation, P.O. Box 1771, 
Long Beach, California 90846-1771, Attention: Business Unit Manager, 
Technical Administrative Support, Dept. L51, Mail Code 2-98. Copies 
may be inspected at the FAA, Transport Airplane Directorate, 1601 
Lind Avenue, SW., Renton, Washington; or at the FAA, Transport 
Airplane Directorate, Los Angeles Aircraft Certification Office 
(ACO), 3229 East Spring Street, Long Beach, California; or at the 
Office of the Federal Register, 800 North Capitol Street, NW., suite 
700, Washington, DC.
    (h) This amendment becomes effective on July 22, 1993.

    Issued in Renton, Washington, on February 28, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-4952 Filed 3-3-94; 8:45 am]
BILLING CODE 4910-13-U