Airworthiness Directives; Bombardier Model DHC-7-100 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-107-AD]

RIN 2120-AA64

Airworthiness Directives; Bombardier Model DHC-7-100 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 all Bombardier Model DHC-7-100

series airplanes. This proposal would require repetitive high frequency

eddy current inspections to detect cracks on the locking pin fittings

of the baggage door and locking pin housings of the fuselage;

repetitive detailed visual inspections to detect cracks of the inner

door structure on all four door locking attachment fittings; and

corrective actions, if necessary. In lieu of accomplishing the

corrective actions, this proposal also would provide a temporary

option, for certain cases, for revising the Airplane Flight Manual

(AFM), and installing a placard. This proposal is prompted by issuance

of mandatory continuing airworthiness information by a foreign civil

airworthiness authority. The actions specified by the proposed AD are

intended to detect and correct fatigue cracking of the baggage door

fittings and the support structure, which could result in structural

failure, and consequent rapid decompression of the airplane during

flight.

DATES: Comments must be received by December 22, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-114,

Attention: Rules Docket No. 99-NM-107-AD, 1601 Lind Avenue, SW.,

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

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

Federal holidays.

The service information referenced in the proposed rule may be

obtained from Bombardier, Inc., Bombardier Regional Aircraft Division,

Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada. This information

may be examined 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, 10 Fifth Street,

Third Floor, Valley Stream, New York.

FOR FURTHER INFORMATION CONTACT: Franco Pieri, Aerospace Engineer,

Airframe and Propulsion Branch, ANE-171, FAA, Engine and Propeller

Directorate, New York Aircraft Certification Office, 10 Fifth Street,

Third Floor, Valley Stream, New York 11581; telephone (516) 256-7526;

fax (516) 568-2716.

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 99-NM-107-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-114, Attention: Rules

Docket No. 99-NM-107-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

Transport Canada Civil Aviation (TCCA), which is the airworthiness

authority for Canada, notified the FAA that an unsafe condition may

exist on all Bombardier Model DHC-7-100 series airplanes. TCCA advises

that fatigue cracks have been reported in the door stop fittings

mounted on the baggage door. Failure of a door stop fitting would

appreciably degrade the structural integrity of the baggage door

installation. This condition, if not corrected, could result in

structural failure, and consequent rapid decompression of the airplane

during flight.

Explanation of Relevant Service Information

Bombardier has issued de Havilland Temporary Revision (TR) 5-100,

dated

December 23, 1998, for Supplementary Inspection Task 52-1 to the de

Havilland Dash 7 Maintenance Manual PSM 1-7-2. The service information

describes procedures for repetitive high frequency eddy current

inspections to detect cracks on the locking pin fittings of the baggage

door and locking pin housings of the fuselage; and repetitive detailed

visual inspections to detect cracks of the inner door structure on all

four door locking attachment fittings. TCCA classified this service

information as mandatory and issued Canadian airworthiness directive

CF-99-03, dated February 22, 1999, in order to assure the continued

airworthiness of these airplanes in Canada.

FAA's Conclusions

This airplane model is manufactured in Canada and is type

certificated for operation in the United States under the provisions of

Sec. 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the

applicable bilateral airworthiness agreement. Pursuant to this

bilateral airworthiness agreement, TCCA has kept the FAA informed of

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

TCCA, 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 registered

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

the actions specified in the service information described previously,

except as discussed below. The proposed AD also would require

corrective actions to be accomplished in accordance with de Havilland

Dash 7 Maintenance Manual PSM 1-7-2. The corrective actions, for

certain cases, involve replacement of any cracked fitting or housing

with a new fitting or housing, as applicable. For certain other

[[Page 63761]]

cases, the corrective actions involve replacement of any cracked

structure with a new support structure, or repair as described below.

In lieu of accomplishing the corrective actions, this proposal also

would provide a temporary option, for certain cases, for revising the

Airplane Flight Manual (AFM), and installing a placard.

Differences Between Proposed Rule and Service Information

Operators should note that, although the service information

specifies that the manufacturer may be contacted for disposition of

certain cracks, this proposal would require the repair of those

conditions to be accomplished in accordance with a method approved by

either the FAA, or the TCCA (or its delegated agent). In light of the

type of repair that would be required to address the identified unsafe

condition, and in consonance with existing bilateral airworthiness

agreements, the FAA has determined that, for this proposed AD, a repair

approved by either the FAA or the TCCA would be acceptable for

compliance with this proposed AD.

Interim Action

This is considered to be interim action until final action is

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

Cost Impact

The FAA estimates that 32 airplanes of U.S. registry would be

affected by this proposed AD, that it would take approximately 3 work

hours per airplane to accomplish the proposed inspections, and that the

average labor rate is $60 per work hour. Based on these figures, the

cost impact of the proposed AD on U.S. operators is estimated to be

$5,760, or $180 per airplane, per inspection cycle.

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.

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), 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

Bombardier, Inc. (Formerly de Havilland, Inc.): Docket 99-NM-107-AD.

Applicability: All Model DHC-7-100 series airplanes,

certificated in any category.

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

preceding applicability provision, regardless of whether it has been

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 (d) 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 detect and correct fatigue cracking in the baggage door

fittings and the support structure, which could result in structural

failure, and consequent rapid decompression of the airplane during

flight, accomplish the following:

Repetitive Inspections

(a) At the latest of the times specified in paragraphs (a)(1)

and (a)(2) of this AD, perform a high frequency eddy current

inspection to detect fatigue cracks of the locking pin fittings of

the baggage door and locking pin housings of the fuselage; and a

detailed visual inspection to detect fatigue cracks of the inner

door structure on all four locking attachment fittings of the

baggage door; in accordance with de Havilland Temporary Revision

(TR) 5-100, dated December 23, 1998, for Supplementary Inspection

Task 52-1 to the de Havilland Dash 7 Maintenance Manual PSM 1-7-2.

Thereafter, repeat the inspections at intervals not to exceed 1,000

flight cycles.

(1) Inspect prior to the accumulation of 12,000 total flight

cycles.

(2) Inspect within 600 flight cycles or 3 months after the

effective date of this AD, whichever occurs later.

Note 2: For the purposes of this AD, a detailed visual

inspection is defined as: ``An intensive visual examination of a

specific structural area, system, installation, or assembly to

detect damage, failure, or irregularity. Available lighting is

normally supplemented with a direct source of good lighting at

intensity deemed appropriate by the inspector. Inspection aids such

as mirror, magnifying lenses, etc., may be used. Surface cleaning

and elaborate access procedures may be required.''

Corrective Actions

(b) If any crack is detected during any inspection required by

paragraph (a) of this AD, prior to further flight, accomplish the

requirements of paragraphs (b)(1) and (b)(2) of this AD, as

applicable, except as provided in paragraph (c) of this AD. For

operators that elect to accomplish the actions specified in

paragraph (c) of this AD: After accomplishment of the replacement

required by paragraph (b)(1) or (b)(2) of this AD, the AFM revision

and placard required by paragraph (c) of this AD may be removed.

(1) If a crack is detected in a baggage door locking pin fitting

or fuselage locking pin housing: Replace the fitting or housing with

a new fitting or housing, as applicable, in accordance with de

Havilland Dash 7 Maintenance Manual PSM 1-7-2.

(2) If a crack is detected in the inner baggage door structure

at the locking attachment fittings: Replace the structure with a new

support structure in accordance with de Havilland Dash 7 Maintenance

Manual PSM 1-7-2, or repair in accordance with a method approved by

the Manager, New York Aircraft Certification Office (ACO), FAA,

Engine and Propeller Directorate, or the Transport Canada Civil

Aviation (or its delegated agent). For a repair method to be

approved by the Manager, New York ACO, as required by this

paragraph, the Manager's approval letter must specifically reference

this AD.

(c) For airplanes on which only one baggage door stop fitting or

its support structure is found cracked at one location, and on which

the pressurization system ``Dump'' function is operational: Prior to

further flight, accomplish the requirements of paragraphs (c)(1) and

(c)(2) of this AD.

[[Page 63762]]

Within 1,000 flight cycles after accomplishment of the requirements

of paragraphs (c)(1) and (c)(2) of this AD, accomplish the

requirements of paragraph (b)(1) or (b)(2) of this AD, as

applicable.

(1) Revise the Limitations Section of the FAA-approved DHC-7

Airplane Flight Manual (AFM), PSM 1-71A-1A, to include the following

statement. This AFM revision may be accomplished by inserting a copy

of this AD into the AFM.

Flight is restricted to unpressurized flight below 10,000 feet

mean sea level (MSL). The airplane must be operated in accordance

with DHC-7 AFM, PSM 1-71A-1A, Supplement 20.

(2) Install a placard on the cabin pressure control panel or in

a prominent location that states the following:

DO NOT PRESSURIZE THE AIRCRAFT UNPRESSURIZED FLIGHT PERMITTED

ONLY IN ACCORDANCE WITH DHC-7 AFM PSM 1-71A-1A, SUPPLEMENT 20 FLIGHT

ALTITUDE LIMITED TO 10,000 FEET MSL OR LESS.

Alternative Methods of Compliance

(d) 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 3: Information concerning the existence of approved

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

obtained from the New York ACO.

Special Flight Permits

(e) Special flight permits may be issued in accordance with

Secs. 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.

Note 4: The subject of this AD is addressed in Canadian

airworthiness directive CF-99-03, dated February 22, 1999.

Issued in Renton, Washington, on November 16, 1999.

D.L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 99-30369 Filed 11-19-99; 8:45 am]

BILLING CODE 4910-13-U