Airworthiness Directives; Airbus Industrie Model A320 and A321 Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 95-NM-143-AD]

RIN 2120-AA64

Airworthiness Directives; Airbus Industrie Model A320 and A321

Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: This document proposes the adoption of a new airworthiness

directive (AD) that is applicable to certain Airbus Industrie Model

A320 and A321 series airplanes. This proposal would require replacement

of two elevator aileron computers (ELAC) with ELAC's that contain new

software. This proposal is prompted by reports indicating that some of

these airplanes have experienced uncommanded movements of the ailerons.

The actions specified by the proposed AD are intended to prevent

situations, such as uncommanded rolls during turbulent conditions,

which could lead to reduced controllability of the airplane.

DATES: Comments must be received by February 18, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 95-NM-143-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.

The service information referenced in the proposed rule may be

obtained from Airbus Industrie, 1 Rond Point Maurice Bellonte, 31707

Blagnac Cedex, France. This information may be examined at the FAA,

Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,

Washington.

FOR FURTHER INFORMATION CONTACT:

Charles Huber, Aerospace Engineer, Standardization Branch, ANM-113,

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

Washington 98055-4056; telephone (206) 227-2589; fax (206) 227-1149.

SUPPLEMENTARY INFORMATION:

Comments Invited

h the following statement is made: ``Comments to

Docket Number 95-NM-143-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. 95-NM-143-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, has notified the FAA that an unsafe

condition may exist on certain Airbus Industrie Model A320 and A321

series airplanes. The DGAC advises that it has received reports

indicating that some of these airplanes have experienced uncommanded

rolls; flight crews reported these rolls as ranging from 5 degrees to

30 degrees.

The flight control system for both airplane models uses fly-by-wire

technology. There are situations where the sensitivity of the fly-by-

wire design creates safety concerns. Among these situations are:

When the flaps are set on CONF 3 or CONF FULL and

turbulence is encountered: The flight crew's responses, coupled with

the handling characteristics of the airplane, could cause roll

oscillations.

When the flaps, during approach, have jammed in the fully-

extended position and CONF 3 is subsequently selected: It becomes

difficult for the flight crew to maintain the intended flight path.

When contaminants interfere with proper operation of the

sidestick transducer unit: A possible consequence is the transmission

of transient signals from the sidestick to the ELAC. These signals

could cause the ailerons to ``jerk,'' and result in an uncommanded

roll, regardless of the automatic pilot mode and the stage of flight.

All of these situations, if not corrected, could lead to reduced

controllability of the airplane.

Explanation of Relevant Service Information

unit: A possible consequence is the transmission

of transient signals from the sidestick to the ELAC. These signals

could cause the ailerons to ``jerk,'' and result in an uncommanded

roll, regardless of the automatic pilot mode and the stage of flight.

All of these situations, if not corrected, could lead to reduced

controllability of the airplane.

Explanation of Relevant Service Information

Airbus Industrie has issued Service Bulletin A320-27-1082, dated

April 25, 1995, which describes procedures for replacing the two ELAC's

installed in the aft electronic rack 80VU with two ELAC's that have

been modified. The modifications entail the installation of new

software identified as ``L69J Standard,'' a program that alters the

airplane's flying qualities to reduce the risk of encountering

situations where uncommanded roll and other unsafe conditions are

likely to occur. [This service bulletin references Sextant Service

Bulletins 394512-27-014, dated August 11, 1995 (for airplanes on which

modification 24136P3436 is not installed), and C12370A-27-001, dated

May 2, 1995 (for airplanes on which modification 24136P3436 is

installed), as additional sources of procedural service information for

modification of the ELAC's. Sextant is the supplier of the ELAC's.]

The DGAC classified the Airbus Industrie service bulletin as

mandatory and issued French airworthiness direction (C/N) 95-203-

072(B), dated October 11, 1995, as corrected by Erratum, dated November

8, 1995, in order to assure the continued airworthiness of these

airplanes in France.

FAA's Conclusions

service information for

modification of the ELAC's. Sextant is the supplier of the ELAC's.]

The DGAC classified the Airbus Industrie service bulletin as

mandatory and issued French airworthiness direction (C/N) 95-203-

072(B), dated October 11, 1995, as corrected by Erratum, dated November

8, 1995, in order to assure the continued airworthiness of these

airplanes in France.

FAA's Conclusions

This airplane model is manufactured in French 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 DGAC has kept the FAA informed

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

the 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.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to

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

proposed AD would require replacement of the two ELAC's installed in

the aft electronic rack 80VU with two ELAC's that have been modified to

include L69J Standard software. The actions would be required to be

accomplished in accordance with the Airbus Industrie service bulletin

described previously.

Cost Impact

at is likely to

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

proposed AD would require replacement of the two ELAC's installed in

the aft electronic rack 80VU with two ELAC's that have been modified to

include L69J Standard software. The actions would be required to be

accomplished in accordance with the Airbus Industrie service bulletin

described previously.

Cost Impact

The FAA estimates that 108 Airbus Industrie Model A320 and A321

series airplanes of U.S. registry would be affected by this proposed

AD.

It would take approximately 3 work hours per airplane to accomplish

the proposed actions, at an average labor rate of $60 per work hour.

Required parts would be provided by the manufacturer at no cost to the

operator. Based on these figures, the cost impact of the proposed AD on

U.S. operators is estimated to be $19,440, or $180 per airplane.

The cost impact figure discussed above is based on assumptions that

no operator has yet accomplished any of the proposed requirements of

this AD action, and that no operator would accomplish those actions in

the future if this AD were not adopted.

Regulatory Impact

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

ubstantial 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. 106(g), 40101, 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

Airbus Industrie: Docket 95-NM-143-AD.

Applicability: Model A320 and A321 series airplanes as listed

in Airbus Industrie Service Bulletin A320-27-1082, dated April 25,

1995; certificated in any category.

39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40101, 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

Airbus Industrie: Docket 95-NM-143-AD.

Applicability: Model A320 and A321 series airplanes as listed

in Airbus Industrie Service Bulletin A320-27-1082, dated April 25,

1995; certificated in any category.

Note 1: This AD applies to each airplane identified in the

preceding applicability provision, regardless of whether it has been

otherwise 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 (b) 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 reduced controllability of the airplane, due to

problems associated with the elevator aileron computer (ELAC),

accomplish the following:

(a) Within 1 year after the effective date of this AD, replace

the ELAC's having part numbers (P/N) 3945122307 and/or P/N

C12370AAA01 and located in aft electronics rack 80VU, with modified

ELAC's having P/N 3945122502, in accordance with Airbus Industrie

Service Bulletin A320-27-1082, dated April 25, 1995.

blems associated with the elevator aileron computer (ELAC),

accomplish the following:

(a) Within 1 year after the effective date of this AD, replace

the ELAC's having part numbers (P/N) 3945122307 and/or P/N

C12370AAA01 and located in aft electronics rack 80VU, with modified

ELAC's having P/N 3945122502, in accordance with Airbus Industrie

Service Bulletin A320-27-1082, dated April 25, 1995.

Note 2: Airbus Industrie Service Bulletin A320-27-1082

references Sextant Service Bulletins 394512-27-014, dated August 11,

1995 (for airplanes on which Airbus Industrie modification

24136P3436 has not been installed); and C12370A-27-001, dated May 2,

1995 (for airplanes on which Airbus Industrie modification

24136P3436 has been installed); as additional sources of procedural

service information for modification of the ELAC's.

(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, 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 3: Information concerning the existence of approved

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

obtained from the Standardization Branch, ANM-113.

(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.

Issued in Renton, Washington, on December 31, 1996.

S.R. Miller,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 97-252 Filed 1-6-97; 8:45 am]

BILLING CODE 4910-13-U