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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 99-NM-371-AD] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Supplemental notice of proposed rulemaking; reopening of comment period. 

# SUMMARY:

This document revises an earlier proposed airworthiness directive (AD), applicable to certain Bombardier Model DHC-8-100, -200, and -300 series airplanes, that continues to require a one-time detailed visual inspection to detect damage of the ladder plates and access cover areas of the upper surface of the wings, repair, if necessary, and installation of new O-ring seals. That proposal was prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. This new action revises the inspection requirements of the proposed rule by correcting a reference to a repair manual. The actions specified by this new proposed AD are intended to prevent damage of the upper wing ladder plates, which could result in displacement of the adjacent channel seals and consequent reduced lightning strike protection of the fuel tanks. 

# DATES:

Comments must be received by January 30, 2001. 

# ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-371-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. Comments may be submitted via fax to (425) 227-1232. Comments may also be sent via the Internet using the following address: 9-anm-nprmcomment@faa.gov. Comments sent via fax or the Internet must contain “Docket No. 99-NM-371-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text. 

The service information referenced in the proposed rule may be obtained from Bombardier, Inc., Bombardier Regional Aircraft Division, 123 Garrett Boulevard, Downsview, Ontario M3K 1Y5, 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, New York Aircraft Certification Office, 10 Fifth Street, Third Floor, 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:

James E. Delisio, Aerospace Engineer, Airframe and Propulsion Branch, ANE-171, FAA, New York Aircraft Certification Office, 10 Fifth Street, Third Floor, Valley Stream, New York 11581; telephone (516) 256-7521; 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 action may be changed in light of the comments received. 

Submit comments using the following format: 
    - Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
    - For each issue, state what specific change to the proposed AD is being requested.
    - Include justification (e.g., reasons or data) for each request.

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 action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 99-NM-371-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-371-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. 

## Discussion 

                    A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to add an airworthiness directive (AD), applicable to certain Bombardier Model DHC-8-100, -200, and -300 series airplanes, was                           ( print page 1058)                        published as a notice of proposed rulemaking (NPRM) in the                     **Federal Register**                     on February 10, 2000 (65 FR 6565). That NPRM would have required a one-time detailed visual inspection to detect damage of the ladder plates and access cover areas of the upper surface of the wings, repair, if necessary, and installation of new O-ring seals. That NPRM was prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority.                 

## Comments 

Due consideration has been given to the comments received in response to the original NPRM: 

## Requests to Correct a Reference to a Bombardier Repair Manual 

One commenter requests correcting a reference to a repair manual in the original NPRM. That commenter states that the limits for correcting fretting corrosion are included in the Generic Structural Repair Schemes Manual PSM 1-8-3RS instead of in the Structural Repair Manual, as cited in paragraphs (a)(2) and (a)(3) of the original NPRM. A second commenter agrees with the first commenter's statements. 

The FAA concurs that Generic Structural Repair Schemes Manual PSM 1-8-3RS is one of the correct references for specifying the limits for correcting fretting and corrosion. A second appropriate reference is Generic Structural Repair Schemes Manual PSM 1-82-3RS (Chapter 57 Contents and Repair Index). We point out that Bombardier Service Bulletin 8-57-41, Revision ‘C’ dated August 4, 2000, cites both of those references. In light of this, we have added both references in paragraphs (a)(2) and (a)(3) of this supplemental NPRM. 

## Requests To Change the Revision Level of the Service Bulletin 

Two commenters state that the original NPRM should cite Bombardier Service Bulletin 8-57-41, Revision “B”, dated December 22, 1999, instead of Revision “A”, dated July 28, 1999. One of the commenters adds that Revision “B” includes procedures for inspecting the long-range fuel tanks. 

Although the FAA does not concur that Revision “B” of the service bulletin should be cited, we have cited a later revision of the service bulletin, Revision “C”, in this supplemental NPRM. Revision “C” includes additional changes and corrections to earlier revisions of the service bulletin, adds additional work for the operators, and revises the inspection and installation procedures for long-range fuel tanks. We have changed the reference in paragraph (a) of this supplemental NPRM to cite Revision “C” of the service bulletin. 

## Requests To Extend the Compliance Time 

Two commenters request extending the compliance time for the one-time detailed visual inspection and the corrective actions specified by the original NPRM. Both commenters state that the compliance time of 60 days is too restrictive and will result in airplanes being removed from service for an extended downtime. They also consider that a 60-day compliance time would cause particular problems for U.S. operators with large fleets of Model DHC-8 series airplanes. One of the commenter suggests extending the compliance time to 12 months, and adds that its 10-year service history shows that no significant instances of corrosion or fretting occurred on its airplanes with the larger O-ring seals installed. That same commenter adds that Canadian airworthiness directive CF-99-20 specified a compliance time of 5 months for a much smaller fleet. The second commenter suggests that the action specified by the original NPRM be accomplished at the next maintenance period when the fuel tanks are accessed. 

The FAA partially concurs with the commenters’ requests to extend the compliance time. Analysis of the data sent by both commenters, which includes long-term service history, shows that the use of larger O-ring seals has not presented a serious problem in the U.S. fleet. For these reasons, we have extended the compliance time from 60 days to 9 months after the effective date of this AD, or at the next maintenance period during which the fuel tanks are accessed, whichever occurs earlier. 

We consider that such an extension will avoid grounding airplanes unnecessarily, while ensuring timely replacement of the seals. We have revised paragraph (a) of this proposed AD accordingly.

## Requests To Allow the Use of Alternative Solvents 

One commenter states that the previously referenced service bulletin specifies the use of solvents that typically are not available [or are not approved] for use in the United States. The commenter suggests that the original NPRM should allow operators to use other appropriate solvents that do not pose significant safety hazards for maintenance personnel. This would avoid requiring operators to request an alternative method of compliance (AMOC) for using other appropriate solvents. A second commenter agrees with the first commenter's statements. 

                    The FAA concurs with the commenters’ suggestions to allow operators to make repairs using alternative solvents that are approved per standard industry maintenance practices without having to request an AMOC. We have added                     **Note 3**                     in this proposed AD to notify operators of such an alternative.                 

## Explanation of Applicability 

The Canadian airworthiness directive specifies, for certain Model DHC-8 series airplanes, serial numbers 003 through 543. However, the service bulletin specifies serial numbers 003 through 528 and 531, and clarifies that the specified modification will be incorporated before delivery on applicable Model DHC-8 series airplanes, having serial numbers 529, 530, and 532 through 543. For this reason, the applicability of this supplemental NPRM parallels the effectivity of the service bulletin. 

## Conclusion 

Since the scope of the originally proposed rule has been expanded, the FAA has determined that it is necessary to reopen the comment period to provide additional opportunity for public comment. 

## Cost Impact 

There are approximately 516 Model DHC-8-100, -200, and  -300 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 235 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 6 work hours per airplane to accomplish the proposed actions, 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 $84,600, or $360 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. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.                           ( print page 1059)    

## Regulatory Impact 

The regulations proposed herein would not have a substantial direct effect 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, it is determined that this proposal would not have federalism implications under Executive Order 13132. 

                    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. 

§ 39.13 

2. Section 39.13 is amended by adding the following new airworthiness directive: 

**Bombardier, Inc. (Formerly de Havilland, Inc.):**                                 Docket 99-NM-371-AD.                             

*Applicability:*                                 Model DHC-8-100, -200, and -300 series airplanes, having serial numbers 003 through 528 inclusive and 531; 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 (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 damage of the upper wing ladder plates, which could result in displacement of the adjacent channel seals and consequent reduced lightning strike protection of the fuel tanks, accomplish the following: 

## Inspection and Repair 

(a) Within 9 months or at the next maintenance period during which the fuel tanks are accessed after the effective date of this AD, whichever occurs earlier: Perform a one-time detailed visual inspection to detect damage (i.e., fretting and/or corrosion) of the ladder plates and access cover areas of the upper surface of the wings per paragraph III.A., III.B., or III.C., as applicable, of the Accomplishment Instructions of Bombardier Service Bulletin 8-57-41, Revision ‘C’, dated August 4, 2000. 

# 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.” 

(1) If no damage is detected, prior to further flight, install new 0.103-inch-diameter O-ring seals per paragraph III.A., III.B., or III.C., as applicable, of the Accomplishment Instructions of the service bulletin. 

(2) If any damage is detected that is within the limits specified in Generic Structural Repair Schemes Manual PSM 1-8-3RS or PSM 1-82-3RS (Chapter 57 Contents and Repair Index), before further flight, repair the damage per Generic Structural Repair Schemes Manual PSM 1-8-3RS or PSM 1-82-3RS (Chapter 57 Contents and Repair Index), and install new 0.103-inch-diameter O-ring seals per paragraph III.A., III.B., or III.C., as applicable, of the Accomplishment Instructions of the service bulletin. 

(3) If any damage is detected that is outside the limits specified in Generic Structural Repair Schemes Manual PSM 1-8-3RS or PSM 1-82-3RS (Chapter 57 Contents and Repair Index), before further flight, repair per a method approved by the Manager, New York Aircraft Certification Office (ACO), FAA, and install new 0.103-inch-diameter O-ring seals. 

# Note 3:

Although the Bombardier service bulletin includes references to solvents that are not available for use in the United States, operators may use appropriate substitute solvents per standard industry maintenance practices.

## Alternative Methods of Compliance 

(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, New York ACO, FAA. 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 4:

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 

(c) Special flight permits may be issued per §§ 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 5:

The subject of this AD is addressed in Canadian airworthiness directive CF-99-20, dated July 20, 1999. 

Issued in Renton, Washington, on December 29, 2000. 

Donald L. Riggin, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. 

[FR Doc. 01-342 Filed 1-4-01; 8:45 am] 

BILLING CODE 4910-13-U