Airworthiness Directives; Boeing Model 747-400 Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 94-NM-61-AD; Amendment 39-8970; AD 94-14-21]

Airworthiness Directives; Boeing Model 747-400 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD),

applicable to certain Boeing Model 747-400 series airplanes, that

requires a revision to the Flap Control Unit input wiring. This

amendment is prompted by reports of disconnection of the Landing Gear

Module electrical connectors, which can result in the loss of the

primary, secondary, and alternate control of the flaps. The actions

specified by this AD are intended to prevent the possibility of an all-

flaps-up landing due to the loss of control of all flap operations.

DATES: Effective August 10, 1994. The incorporation by reference of

certain publications listed in the regulations is approved by the

Director of the Federal Register as of August 10, 1994.

ADDRESSES: The service information referenced in this AD may be

obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle,

Washington 98124-2207. 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 Office of

the Federal Register, 800 North Capitol Street, NW., suite 700,

Washington, DC.

FOR FURTHER INFORMATION CONTACT: Kathi Ishimaru, Aerospace Engineer,

Systems & Equipment Branch, ANM-130S, Seattle Aircraft Certification

Office, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW.,

Renton, Washington 98055-4056; telephone (206) 227-2674; fax (206) 227-

1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal

Aviation Regulations (14 CFR part 39) to include an airworthiness

directive (AD) that is applicable to certain Boeing Model 747-400

series airplanes was published in the Federal Register on May 12, 1994

(59 FR 24671). That action proposed to require a revision to the Flap

Control Unit (FCU) input wiring.

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the comments received.

One commenter, Boeing, requests that the discussion of the

addressed unsafe condition that appeared in the preamble to the notice

be clarified. In that preamble, the FAA stated that, if the landing

gear module connectors become disconnected, all FCU modes of flap

operation (primary, secondary, and alternate control of flaps) could be

lost. The commenter suggests that the discussion would have been more

precise if it had contained information to indicate that the landing

gear module includes the ALTN ARM FLAPS switch and the ALTN FLAPS

position selector used to control the leading and trailing edge flaps

in the alternate mode. The FAA acknowledges this information.

This same commenter requests that the proposal be revised to cite

the latest revision of Boeing Service Bulletin 747-27A2346 as the

source for modification procedures. The FAA concurs. Since issuance of

the notice, the FAA has reviewed and approved Revision 1 of Boeing

Service Bulletin 747-27A2346, dated May 19, 1994. This revision

contains a correction to a type of wire that had been called out in the

original version of the service bulletin; this correction ensures that

the wire and its associated solder sleeve are metalurgically

compatible. In order to ensure that the correct wiring modification

assembly is installed on the affected airplanes, the FAA has determined

that the revised service bulletin should be cited as the appropriate

source of service information for complying with the requirements of

this rule. The final rule has been revised accordingly. The FAA has

confirmed that no U.S. operators have yet modified any affected

airplane in accordance with the original service bulletin; therefore,

by citing the revised service bulletin, the final rule will impose no

additional economic burden on any U.S. operator.

One commenter requests that the compliance time be extended from

the proposed 30 days to 90 days, due to a possible parts availability

problem. This commenter states that it does not normally stock the

required parts and materials to accomplish the proposed requirements of

the rule. This commenter has ordered these parts from a supplier and is

currently waiting to obtain them. Additionally, this commenter points

out that the manufacturer's service bulletin, referenced in the

proposal, recommends 60 days for modification. The FAA does not concur

with the commenter's request. In developing an appropriate compliance

time for this action, the FAA considered not only the degree of urgency

associated with addressing the subject unsafe condition, but the

manufacturer's recommendation as to an appropriate compliance time, the

availability of required parts, and the practical aspect of installing

the required modification within a maximum interval of time allowable

for all affected airplanes to continue to operate without compromising

safety. The FAA points out that the parts required for the wiring

modification are readily available; therefore, obtaining them within

the proposed compliance time should not pose a problem for any affected

operator. Further, the FAA took into account the 60-day compliance time

recommended by the manufacturer, as well as the number of days required

for the rulemaking process; in consideration of these factors, the FAA

finds that 30 days after the effective date of this final rule will

fall approximately at the same time for compliance as recommended by

the manufacturer. However, under the provisions of paragraph (b) of the

final rule, the FAA may approve requests for adjustments to the

compliance time if data are submitted to substantiate that such an

adjustment would provide an acceptable level of safety.

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 change previously

described. The FAA has determined that this change will neither

increase the economic burden on any operator nor increase the scope of

the AD.

There are approximately 300 Model 747-400 series airplanes of the

affected design in the worldwide fleet. The FAA estimates that 34

airplanes of U.S. registry will be affected by this AD, that it will

take approximately 10 work hours per airplane to accomplish the

required actions, and that the average labor rate is $55 per work hour.

Required parts will cost approximately $200 per airplane. Based on

these figures, the total cost impact of the AD on U.S. operators is

estimated to be $25,500, or $750 per airplane.

The total 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.

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.

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 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:

94-14-21 Boeing: Amendment 39-8970. Docket 94-NM-61-AD.

Applicability: Model 747-400 airplanes having line numbers 696

through 1019, inclusive, and 1021 through 1026, inclusive;

certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent the possibility of an all-flaps-up landing due to the

loss of control of flap operations, accomplish the following:

(a) Within 30 days after the effective date of this AD, revise

the Flap Control Unit (FCU) input wiring in accordance with Boeing

Alert Service Bulletin 747-27A2346, Revision 1, dated May 19, 1994.

(b) 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: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Seattle ACO.

(c) 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.

(d) The wiring revision shall be done in accordance with Boeing

Alert Service Bulletin 747-27A2346, Revision 1, dated May 19, 1994.

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 Boeing Commercial Airplane Group,

P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be

inspected at the FAA, Transport Airplane Directorate, 1601 Lind

Avenue, SW., Renton, Washington; or at the Office of the Federal

Register, 800 North Capitol Street NW., suite 700, Washington, DC.

(e) This amendment becomes effective on August 10, 1994.

Issued in Renton, Washington, on July 1, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-16535 Filed 7-8-94; 8:45 am]

BILLING CODE 4910-13-U