Airworthiness Directives; Airbus Model A310 and A300-600 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-145-AD]

Airworthiness Directives; Airbus Model A310 and A300-600 Series

Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness

directive (AD) that is applicable to certain Airbus Model A310 and

A300-600 series airplanes. This proposal would require that certain

flight control computers be modified so that the autopilot will

disengage whenever the airplane is in the ``go-around'' mode. This

proposal is prompted by an accident in which the flight crew may have

attempted a go-around while the airplane was in an out-of-trim

condition. The actions specified by the proposed AD are intended to

prevent severely reduced controllability of the airplane due to an out-

of-trim condition between the trimmable horizontal stabilizer and the

elevator.

DATES: Comments must be received by November 28, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-103,

Attention: Rules Docket No. 94-NM-145-AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055-4056. Comments may be inspected at this

location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except

Federal holidays.

Information pertaining to this proposed rule may be obtained from

or examined at the FAA, Transport Airplane Directorate, Rules Docket,

1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Stephen Slotte, Aerospace Engineer,

Standardization Branch, ANM-113, FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206)

227-2797; fax (206) 227-1320.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the

proposed rule by submitting such written data, views, or arguments as

they may desire. Communications shall identify the Rules Docket number

and be submitted in triplicate to the address specified above. All

communications received on or before the closing date for comments,

specified above, will be considered before taking action on the

proposed rule. The proposals contained in this notice may be changed in

light of the comments received.

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the proposed rule. All

comments submitted will be available, both before and after the closing

date for comments, in the Rules Docket for examination by interested

persons. A report summarizing each FAA-public contact concerned with

the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments

submitted in response to this notice must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket Number 94-NM-145-AD.'' The postcard will be date stamped and

returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request

to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules

Docket No. 94-NM-145-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

The Direction Generale de l'Aviation Civile (DGAC), which is the

airworthiness authority for France, recently notified the FAA that an

unsafe condition may exist on certain Airbus Model A310 and A300-600

series airplanes. The French DGAC advises that a Model A300-600 series

airplane was recently involved in an accident during which the flight

crew may have attempted a go-around while the airplane was in an out-

of-trim condition. Investigation into the cause of this out-of-trim

condition revealed that the flight crew may have attempted to override

the autopilot while it was engaged in the COMMAND mode. If the airplane

is in pitch axis, and the autopilot is overridden for prolonged periods

by the flight crew via manual input from the control column, and if the

autopilot is subsequently disengaged, the resultant out-of-trim

condition between the trimmable horizontal stabilizer and the elevator

could reduce controllability of the airplane.

Further investigation indicates that the design of Model A300-600

series airplanes does not provide for disengagement of the autopilot in

a manner that would allow for manual input from the control column

without adversely affecting controllability of the airplane. The design

of Model A310 series airplanes is identical in this respect to Model

A300-600 series airplanes.

The French DGAC issued French Airworthiness Directive 94-185-

165(B), dated August 17, 1994, in order to assure the continued

airworthiness of these airplanes in France. The French AD requires

modification of FCC's having part numbers (P/N) B216ABM6, B350AAM1,

B350AAM2, B350AAM3, and B470ABM1 (for Model A310 series airplanes); and

P/N's B297AAM3, B297AAM4, B297AAM5, and B470AAM1 (for Model A300-600

series airplanes).

The French AD references Airbus Service Bulletins A310-22-2036,

dated December 14, 1993 (for Model A310 series airplanes), and A300-22-

6021, Revision 1, dated December 24, 1993 (for Model A300-600 series

airplanes), as the appropriate sources of service information to

accomplish the modification of the FCC's. However, Airbus Service

Bulletin A310-22-2036, dated December 14, 1993, describes procedures

for modification of only one of the FCC's, P/N B470ABM1, which is

installed on Model A310 series airplanes; while Airbus Service Bulletin

A300-22-6021, Revision 1, dated December 24, 1993, describes procedures

for modification of only one of the FCC's, P/N B470AAM1, which is

installed on Model A300-600 series airplanes. Upon accomplishment of

this software modification, the autopilot will disengage whenever the

airplane is in the ``go-around'' mode above 400 feet radio altitude and

whenever the pilot attempts to override the autopilot by exerting a

certain amount of manual force on the control column.

This airplane model is manufactured in France and is type

certificated for operation in the United States under the provisions of

section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and

the applicable bilateral airworthiness agreement. Pursuant to this

bilateral airworthiness agreement, the French DGAC has kept the FAA

informed of the situation described above. The FAA has examined the

findings of the French DGAC, reviewed all available information, and

determined that AD action is necessary for products of this type design

that are certificated for operation in the United States.

Since an unsafe condition has been identified that is likely to

exist or develop on other airplanes of the same type design registered

in the United States, the proposed AD would require modification of

FCC's having P/N's B216ABM6, B350AAM1, B350AAM2, and B350AAM3 (for

Model A310 series airplanes); and P/N's B297AAM3, B297AAM4, and

B297AAM5 (for Model A300-600 series airplanes). Since the manufacturer

has not yet developed a modification for these FCC's, these

modifications are to be accomplished in accordance with a method

approved by the FAA.

This is considered to be interim action until final action is

identified, at which time the FAA may consider further rulemaking.

Modification of FCC's having P/N's B470ABM1 (for Model A310 series

airplanes) and B470AAM1 (for Model A300-600 series airplanes) has been

addressed in a separate rulemaking action (reference Airworthiness

Directive Rules Docket Number 94-NM-134-AD). Since the manufacturer has

advised that an ample number of required parts will be available for

modification of FCC's having these two part numbers, and in light of

the degree of urgency associated with the subject unsafe condition, the

FAA finds that modification of those FCC's must be accomplished sooner

than the modification of the FCC's addressed in this proposal. That AD

action also requires a revision to the FAA-approved Airplane Flight

Manual (AFM) that warns the flight crew to avoid overriding the

autopilot while the airplane is in the COMMAND mode and cautions the

flight crew to check the status of the autopilot in the event the

flight controls respond abnormally.

The FAA estimates that 15 Model A310 series airplanes and 36 Model

A300-600 series airplanes of U.S. registry would be affected by this

proposed AD.

Since the manufacturer has not yet developed one specific

modification commensurate with the requirements of this proposal, the

FAA is unable at this time to provide a specific information as to the

number of work hours or cost of parts that would be required to

accomplish the proposed modification. A further problem in developing a

specific cost estimate is the fact that modification costs are expected

to vary from operator to operator and from airplane to airplane

depending upon airplane configuration. The proposed compliance time of

24 months should provide ample time for the development, approval, and

installation of an appropriate modification.

However, based on similar modifications accomplished previously on

other FCC's installed on other airplane models, the FAA can reasonably

estimate that the proposed modification may require as few as 2 work

hours or as many as 50 work hours to accomplish, at an average labor

rate of $55 per work hour. The cost of required parts could range from

a negligible amount to as much as $1,500 per airplane. Based on these

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

estimated to be between $5,610 ($110 per airplane) and $216,750 ($4,250

per airplane).

As indicated earlier in this preamble, the FAA specifically invites

the submission of comments and other data regarding this economic

aspect of proposal.

The regulations proposed herein would 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

proposal would not have sufficient federalism implications to warrant

the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this proposed

regulation (1) is not a ``significant regulatory action'' under

Executive Order 12866; (2) is not a ``significant rule'' under the DOT

Regulatory Policies and Procedures (44 FR 11034, February 26, 1979);

and (3) if promulgated, 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 copy of the draft

regulatory evaluation prepared for this action is contained in the

Rules Docket. A copy of it may be obtained by contacting the Rules

Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration proposes to amend

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:

Airbus Industrie: Docket 94-NM-145-AD.

Applicability: Model A310 series airplanes equipped with Flight

Control Computers (FCC) having part number (P/N) B216ABM6, B350AAM1,

B350AAM2, or B350AAM3; and Model A300-600 series airplanes equipped

with FCC's having P/N B297AAM3, B297AAM4, or B297AAM5; certificated

in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent reduced controllability of the airplane, accomplish

the following:

(a) Within 24 months after the effective date of this AD, modify

the FCC's in accordance with a method approved by the Manager,

Standardization Branch, ANM-113, FAA, Transport Airplane

Directorate.

(b) As of 24 months after the effective date of this AD, no

person shall install an FCC having P/N B216ABM6, B350AAM1, B350AAM2

or B350AAM3 on any Model A310 series airplane; and P/N B297AAM3,

B297AAM4, or B297AAM5 on any Model A300-600 series airplane.

(c) 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, Standardization Branch, ANM-113,

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,

Standardization Branch, ANM-113.

Note: Information concerning the existence of approved

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

obtained from the Standardization Branch, ANM-113.

(d) 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.

Issued in Renton, Washington, on October 7, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-25582 Filed 10-14-94; 8:45 am]

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