Airworthiness Directives; Bombardier (Formerly Canadair) Model CL-600-2B19 (Regional Jet Series 100) Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 93-NM-213-AD; Amendment 39-9055; AD 94-22-06]

Airworthiness Directives; Bombardier (Formerly Canadair) Model

CL-600-2B19 (Regional Jet Series 100) 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 Bombardier Model CL-600-2B19 series airplanes,

that requires modification of the stall protection system (SPS) input

wiring; a revision to the FAA-approved Airplane Flight Manual (AFM) to

specify that a pre-flight check of the slip/skid indications must be

conducted prior to engine start; and modification of the stall

protection computer (SPC) to accept restored dual attitude and heading

reference system (AHRS) input. This amendment is prompted by a report

that the AHRS could send conflicting input to the SPC on the airplane.

The actions specified by this AD are intended to prevent the loss of

stall warning protection on the airplanes.

DATES: Effective December 12, 1994.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of December 12, 1994.

ADDRESSES: The service information referenced in this AD may be

obtained from Bombardier, Inc., Canadair, Aerospace Group, P.O. Box

6087, Station Centreville, Montreal, Quebec H3C 3G9, Canada. 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, Engine and Propeller

Directorate, New York Aircraft Certification Office, 181 South Franklin

Avenue, Valley Stream, New York; or at the Office of the Federal

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

FOR FURTHER INFORMATION CONTACT: Peter Cuneo, Electrical Engineer,

Systems and Equipment Branch, ANE-173, FAA, Engine and Propeller

Directorate, New York Aircraft Certification Office, 181 South Franklin

Avenue, Room 202, Valley Stream, New York 11581; telephone (516) 791-

6427; fax (516) 791-9024.

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 Bombardier Model CL-600-

2B19 (Regional Jet Series 100) series airplanes was published in the

Federal Register on March 4, 1994 (59 FR 10340). That action proposed

to require modification of the stall protection system (SPS) input

wiring; a revision to the Normal Procedures section of the FAA-approved

Airplane Flight Manual (AFM) to specify that a pre-flight check of the

slip/skid indications must be conducted prior to engine start; and

modification of the attitude and heading reference system (AHRS) to

restore the dual AHRS inputs to the SPC.

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 requests that the FAA revise the final rule to

indicate that it is not the AHRS that will be modified, but the stall

protection computer (SPC). The FAA concurs, and has revised the

preamble and paragraph (c) of the final rule to clarify its intent that

the SPC be modified to restore the dual AHRS inputs to the SPC.

The commenter also requests that the proposed compliance time of 6

months for modification of the SPC, as specified in paragraph (c) of

the proposed rule, be extended due to the complex nature of the SPC

modification and the need to modify additional equipment to support the

SPC change. The commenter proposes a target date of April 4, 1995, for

accomplishment of the modification. As justification for this suggested

extension, the commenter states that the SPC software will detect a

loss of AHRS input to both SPC channels, and a ``STALL FAIL'' amber

message will be displayed; additionally, the AFM defines abnormal

procedures to be followed when loss of the SPS occurs. The commenter

adds that there are several components in the SPS that can fail and

cause the loss of stall protection on any one flight. The commenter

believes that the loss of AHRS input is no worse than, and the system

is just as reliable as, a system with two independent AHRS inputs.

The FAA does not concur. Compliance times for AD's are normally

based on a parameter related to failure of a particular component. The

FAA has determined that there is no apparent direct relationship

between the transmittal of conflicting input from the AHRS to the SPC

(and subsequent loss of stall warning protection on the airplane) and a

calendar date. Therefore, the FAA does not consider that the compliance

time for modification of the SPC should be expressed in terms of a

calendar date, as suggested by the commenter.

Further, in developing a compliance time for this requirement of

the rule, the FAA considered not only the safety implications, but 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. In light of these items, the FAA finds that a compliance time

of 6 months is appropriate. (Additionally, based on the effective date

of this final rule, the compliance time for operators to perform the

modification will fall close to the calendar date requested by the

commenter.)

A new paragraph (d) has been added to the final rule to clarify the

FAA's intent that modification of the SPC constitutes terminating

action for the AFM revision required by paragraph (b) of this AD.

Therefore, once the SPC is modified, the AFM revision may be removed

from the AFM.

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 changes previously

described. The FAA has determined that these changes will neither

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

the AD.

The FAA estimates that 9 airplanes of U.S. registry will be

affected by this AD, that it will take approximately 2 work hours per

airplane to accomplish the required actions, and that the average labor

rate is $55 per work hour. The cost for required parts will be minimal.

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

operators is estimated to be $990, or $110 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:

94-22-06 Bombardier, Inc. (Formerly Canadair): Amendment 39-9055.

Docket 93-NM-213-AD.

Applicability: Model CL-600-2B19 (Regional Jet Series 100)

series airplanes; serial numbers 7003 through 7026, inclusive;

certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent the loss of stall warning protection on the airplane,

accomplish the following:

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

the stall protection system (SPS) input wiring in accordance with

Canadair Regional Jet Alert Service Bulletin A601R-34-028, Revision

``A,'' dated October 22, 1993.

(b) Prior to further flight after accomplishment of the

modification required by paragraph (a) of this AD, revise the Normal

Procedures section of the FAA-approved Airplane Flight Manual (AFM)

by inserting the following into the AFM as facing page 04-20-13

to advise the flight crew that a pre-flight check of the slip/

skid indications must be accomplished as a ``Before Start'' item.

This may be accomplished by inserting a copy of this AD into the

AFM.

``Change step (4) within paragraph E, Before Start, to read as

follows:

(4) EFIS

Checked and Set

Check that no annunciations are displayed on EFIS

EFIS slip/skid indications

Normal

Indications of a one-half (\1/2\) symbol width lateral

deviation should be interpreted as an AHRS failure.

NOTE

One-half (\1/2\) symbol width displacement corresponds to

approximately one-half displacement on a conventional inclinometer.

EFIS

Set for Departure''

Note 1: Insertion of Canadair Regional Jet Airplane Flight

Manual CSP A-012, Temporary Revision RJ/26, dated October 21, 1993,

in the Normal Procedures section of the AFM is an acceptable method

of compliance with the requirements of paragraph (b) of this AD.

(c) Within 9 months after the effective date of this AD, modify

the stall protection computer (SPC) to accept restored dual attitude

and heading reference system (AHRS) input, in accordance with a

method approved by the Manager, New York Aircraft Certification

Office (ACO), FAA, Engine and Propeller Directorate.

(d) Modification of the SPC in accordance with paragraph (c) of

this AD constitutes terminating action for the AFM revision required

by paragraph (b) of this AD. Following accomplishment of that

modification, the AFM revision may be removed from the FAA-approved

AFM.

(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, New York ACO. Operators shall

submit their requests through an appropriate FAA Principal

Maintenance Inspector, who may add comments and then send it to the

Manager, New York ACO.

Note 2: Information concerning the existence of approved

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

obtained from the New York ACO.

(f) 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.

(g) The modification shall be done in accordance with Canadair

Regional Jet Alert Service Bulletin A601R-34-028, Revision ``A,''

dated October 22, 1993. 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 Bombardier,

Inc., Canadair, Aerospace Group, P.O. Box 6087, Station Centreville,

Montreal, Quebec H3C 3G9, Canada. Copies may be inspected at the

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

Washington; or at the FAA, Engine and Propeller Directorate, New

York Aircraft Certification Office, 181 South Franklin Avenue,

Valley Stream, New York; or at the Office of the Federal Register,

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

(h) This amendment becomes effective on December 12, 1994.

Issued in Renton, Washington, on October 24, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-26721; Filed 11-9-94; 8:45 am]

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