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

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]

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