# AGENCY:

 Federal Aviation Administration, DOT. 

# ACTION:

 Final rule. 

# SUMMARY:

 This amendment supersedes an existing airworthiness directive (AD), applicable to certain British Aerospace (Jetstream) Model 4101 airplanes, that currently requires repetitive detailed visual inspections to detect cracking or other damage of certain diaphragm support structures of the forward equipment compartment; and repair, if necessary. This amendment continues to require repetitive inspections, but also requires replacement of cracked or damaged diaphragm support structures with improved parts, which terminates the requirement for repetitive inspections. This amendment also adds airplanes to the applicability of the AD. This amendment is prompted by the development of improved diaphragms. The actions specified by this AD are intended to prevent failure of the two diaphragms that support the upper structure of the forward equipment compartment, which could accelerate fatigue damage in adjacent structure and result in reduced structural integrity of the airframe. 

# DATES:

 Effective March 2, 2000. 

The incorporation by reference of Jetstream Alert Service Bulletin J41-A53-023, Revision 1, dated July 30, 1999, as listed in the regulations, is approved by the Director of the Federal Register as of March 2, 2000. 

The incorporation by reference of Jetstream Alert Service Bulletin J41-A53-023, dated December 2, 1996, as listed in the regulations, was approved previously by the Director of the Federal Register as of December 23, 1998 (63 FR 63975, November 18, 1998). 

# ADDRESSES:

 The service information referenced in this AD may be obtained from British Aerospace Regional Aircraft American Support, 13850 Mclearen Road, Herndon, Virginia 20171. 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 Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. 

# FOR FURTHER INFORMATION CONTACT:

 Norman B. Martenson, Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2110; fax (425) 227-1149. 

# SUPPLEMENTARY INFORMATION:

                     A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 98-24-01, amendment 39-10888 (63 FR 63975, November 18, 1998), which is applicable to certain British           Aerospace (Jetstream) Model 4101 airplanes, was published in the                     **Federal Register**                     on November 26, 1999 (64 FR 66424). The action proposed to continue to require repetitive detailed visual inspections to detect cracking or other damage of certain diaphragm support structures of the forward equipment compartment; and repair, if necessary. The action also proposed to require replacement of cracked or damaged diaphragm support structures with improved parts, which would terminate the requirement for repetitive inspections. Additionally, the action also proposed to add airplanes to the applicability of the proposed AD.                 

## Comments 

Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were submitted in response to the proposal or the FAA's determination of the cost to the public. 

## Conclusion 

The FAA has determined that air safety and the public interest require the adoption of the rule as proposed. 

## Cost Impact 

There are approximately 59 airplanes of U.S. registry that will be affected by this AD. 

The inspection that is currently required by AD 98-24-01, and retained in this AD, takes approximately 1 work hour per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the inspection requirement of this AD on U.S. operators is estimated to be $3,540, or $60 per airplane, per inspection cycle. 

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the current or 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 adopted herein will 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 final rule does not have federalism implications under Executive Order 13132. 

                    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. 106(g), 40113, 44701. 

§ 39.13

2. Section 39.13 is amended by removing amendment 39-10888 ( 63 FR 63975, November 18, 1998), and by adding a new airworthiness directive (AD), amendment 39-11524, to read as follows:

**2000-02-05 British Aerospace Regional Aircraft [Formerly Jetstream Aircraft Limited; British Aerospace (Commercial Aircraft) Limited]:**                             Amendment 39-11524. Docket 99-NM-306-AD. Supersedes AD 98-24-01, Amendment 39-10888.                        

*Applicability*: Jetstream Model 4101 airplanes, on which British Aerospace Modification JM41384 has not been accomplished, 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 (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 failure of the two diaphragms that support the upper structure of the forward equipment compartment, which could accelerate fatigue damage in adjacent structure and result in reduced structural integrity of the airframe, accomplish the following: 

## Restatement of Certain Requirements of AD 98-24-01

(a) For airplanes having constructors numbers 41004 through 41098 inclusive: Prior to the accumulation of 4,500 total landings, or within 300 landings after December 23, 1998 (the effective date of AD 98-24-01, amendment 39-10888), whichever occurs later: Perform a detailed visual inspection to detect cracking or other damage of the diaphragms installed between station 4 and station 8 of the forward fuselage, in accordance with Jetstream Alert Service Bulletin J41-A53-023, dated December 2, 1996, or Revision 1, dated July 30, 1999. 

# 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 cracking or other damage is detected, repeat the inspection thereafter at intervals not to exceed 3,000 landings. 

(2) If any cracking or other damage is detected, prior to further flight, accomplish the actions required by either paragraph (a)(2)(i) or (a)(2)(ii). After the effective date of this AD, only replacement of the diaphragms in accordance with paragraph (a)(2)(ii) of this AD is acceptable for compliance with the repair requirements of this paragraph. 

(i) Repair the diaphragm in accordance with a method approved by the Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate. Thereafter, repeat the inspection at intervals not to exceed 3,000 landings. 

(ii) Replace both diaphragms with new, improved diaphragms, in accordance with Part 2 of the Accomplishment Instructions of Jetstream Alert Service Bulletin J41-A53-023, Revision 1, dated July 30, 1999. Such replacement constitutes terminating action for the repetitive inspections required by this AD. 

## New Repetitive Inspections and Corrective Actions Required by This AD

(b) For airplanes other than those listed in paragraph (a) of this AD: Prior to the accumulation of 4,500 total landings, or within 300 landings after the effective date of this AD, whichever occurs later, perform a detailed visual inspection to detect cracking or other damage of the diaphragms installed between station 4 and station 8 of the forward fuselage, in accordance with Jetstream Alert Service Bulletin J41-A53-023, Revision 1, dated July 30, 1999. 

(1) If no cracking or other damage is detected, repeat the inspection thereafter at intervals not to exceed 3,000 landings. 

(2) If any cracking or other damage is detected, prior to further flight, replace both diaphragms with new, improved diaphragms, in accordance with Part 2 of the Accomplishment Instructions of Jetstream Alert Service Bulletin J41-A53-023, Revision 1, dated July 30, 1999. Such replacement constitutes terminating action for the repetitive inspections required by this AD. 

(c) Replacement of diaphragms with new, improved diaphragms, in accordance with Part 2 of the Accomplishment Instructions of Jetstream Alert Service Bulletin J41-A53-023, Revision 1, dated July 30, 1999, constitutes terminating action for the requirements of this AD. 

## 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, International Branch, ANM-116, 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, International Branch, ANM-116. 

# Note 3:

 Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116.

## Special Flight Permits 

(e) 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. 

## Incorporation by Reference 

(f) Except as provided by paragraph (a)(2)(i) of this AD, the actions shall be done in accordance with Jetstream Alert Service Bulletin J41-A53-023, dated December 2, 1996, or Jetstream Alert Service Bulletin J41-A53-023, Revision 1, dated July 30, 1999. 

(1) The incorporation by reference of Jetstream Alert Service Bulletin J41-A53-023, Revision 1, dated July 30, 1999, is approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. 

(2) The incorporation by reference of Jetstream Alert Service Bulletin J41-A53-023, dated December 2, 1996, was approved previously by the Director of the Federal Register as of December 23, 1998 (63 FR 63975, November 18, 1998). 

(3) Copies may be obtained from British Aerospace Regional Aircraft American Support, 13850 Mclearen Road, Herndon, Virginia 20171. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. 

(g) This amendment becomes effective on March 2, 2000.

Issued in Renton, Washington, on January 19, 2000. 

Donald L. Riggin, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

[FR Doc. 00-1713 Filed 1-26-00; 8:45 am] 

BILLING CODE 4910-13-U