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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 2000-NM-295-AD] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Notice of proposed rulemaking (NPRM). 

# SUMMARY:

This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Boeing Model 737-200 and -300 series airplanes, that currently requires a one-time inspection to detect cracks of the lower frames and reinforcing angles of the main deck cargo door where the door latch fittings attach between certain fuselage stations and water lines, and replacement of any cracked part with a new part having the same part number. That AD was prompted by reports that, during the inspections required by the existing AD, cracks were found in the reinforcing angles of the main deck cargo door frame. This action would require, among other actions, an inspection to detect cracks of the lower frames and reinforcing angles of the main deck cargo door; replacement of any lower frame or reinforcing angle of the main deck cargo door when it has reached its maximum life limit. The actions specified by the proposed AD are intended to detect and correct cracking of the lower portion of the main deck cargo door frames, which could result in sudden depressurization, loss or opening of the main deck cargo door during flight, and loss of control of the airplane. 

# DATES:

Comments must be received by November 16, 2000. 

# ADDRESSES:

                        Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-295-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. Comments may be submitted via fax to (425) 227-1232. Comments may also be sent via the Internet using the following address: 9-anm-                              ( print page 61290)    nprmcomment@faa.gov. Comments sent via fax or the Internet must contain “Docket No. 2000-NM-295-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 Pemco World Air Services, 100 Pemco Drive, Dothan, AL 36303. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. 

# FOR FURTHER INFORMATION CONTACT:

Rany Azzi, Aerospace Engineer, Airframe and Propulsion Branch, ACE-117A, FAA, Atlanta Aircraft Certification Office, One Crown Center, 1895 Phoenix Boulevard, Suite 450, Atlanta, Georgia 30337-2748, telephone (770) 703-6083; fax (770) 703-6097. 

# 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. 

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 notice must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2000-NM-295-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. 2000-NM-295-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. 

## Discussion 

On August 18, 2000, the FAA issued AD 2000-17-51, amendment 39-11877 (65 FR 51752, August 25, 2000), applicable to certain Boeing Model 737-200 and -300 series airplanes, to require a one-time inspection to detect cracks of the lower frames and reinforcing angles of the main deck cargo door where the door latch fittings attach between certain fuselage stations (FS) and water lines (WL), and replacement of any cracked part with a new part having the same part number. That action was prompted by reports that, during the inspections required by the existing AD, cracks were found in the reinforcing angles of the main deck cargo door frame. The requirements of that AD are intended to detect and correct cracking of the lower portion of the main deck cargo door frames, which could result in sudden depressurization, loss or opening of the main deck cargo door during flight, and loss of control of the airplane. 

In the preamble of AD 2000-17-51, the FAA indicated that the actions required by that AD were considered “interim action” and that further rulemaking action was being considered to supersede that AD to require replacement of the main deck cargo door frames and reinforcing angles that have accumulated 7,000 or more total flight cycles with new parts. The FAA now has determined that further rulemaking action is indeed necessary, and this proposed AD follows from that determination. 

## Actions Since Issuance of Previous Rule 

Since the issuance of that AD, the FAA has reviewed and approved Pemco Service Bulletin 737-52-0037, Revision 2, dated September 13, 2000, including Attachment 1, dated August 10, 2000. The service bulletin describes the following procedures: 
    - A high frequency eddy current (HFEC) inspection to detect cracks of the lower frames and reinforcing angles of the main deck cargo door where the door latch fittings attach between FS 361.87 and FS 498.12 and WL 202.35 and WL 213.00;
    - Repetitive HFEC inspections of existing and replaced parts; and
    - Replacement of any lower frame or reinforcing angle of the main deck cargo door, if cracks are detected or when the frame or angle has reached its maximum life limit (i.e. 7,000 flight cycles), with a new part having the same part number.

Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition. 

## Explanation of Requirements of Proposed Rule 

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would supersede AD 2000-17-51 to require accomplishment of the actions specified in the service bulletin described previously. 

## Cost Impact 

There are approximately 35 Model 737-200 and -300 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 2 airplanes of U.S. registry would be affected by this proposed AD. 

It would take approximately 500 work hours per airplane to accomplish the proposed inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the inspection proposed by this AD on U.S. operators is estimated to be $60,000, or $30,000 per airplane. 

It would take approximately 128 work hours per airplane to accomplish the proposed replacement, at an average labor rate of $60 per work hour. Required parts would cost approximately $15,521 per airplane. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $46,402, or $23,201 per airplane. 

                    The cost impact figures discussed above are 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. 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 61291)    

## 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 removing amendment 39-11877 (65 FR 51752, August 25, 2000), and by adding a new airworthiness directive (AD), to read as follows: 

**Boeing:**                                 Docket 2000-NM-295-AD. Supersedes AD 2000-17-51, Amendment 39-11877.                             

*Applicability:*                                 Model 737-200 and −300 series airplanes, equipped with a main deck cargo door installed in accordance with Supplemental Type Certificate (STC) SA2969SO; 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 (c)(1) 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 cracking of the lower portion of the main deck cargo door frames, which could result in sudden depressurization, loss or opening of the main deck cargo door during flight, and loss of control of the airplane, accomplish the following: 

## Actions Addressing Door Frames or Reinforcing Angles That Have Been Replaced 

(a) For airplanes on which any door frame or reinforcing angle at the location where the door latch fittings attach between fuselage station (FS) 361.86 and FS 298.12 and water line (WL) 202.35 and WL 213.00 has been replaced before the effective date of this AD: Do the actions specified in paragraphs (a)(1) and (a)(2) of this AD per the Accomplishment Instructions of Pemco Service Bulletin 737-52-0037, Revision 2, dated September 13, 2000, including Attachment 1, dated August 10, 2000. 

(1) Within 3,000 flight cycles after accomplishment of the replacement, do a high frequency eddy current (HFEC) inspection to detect cracks of the replaced lower frames or replaced reinforcing angles of the main deck cargo door, as applicable. 

(i) If no crack is detected, repeat the HFEC inspection thereafter at intervals of 1,300 flight cycles on the replaced part. 

(ii) If any crack is detected, before further flight, replace the cracked part with a new part having the same part number per the service bulletin. Within 3,000 flight cycles after accomplishment of the replacement, do the HFEC inspection required by paragraph (a)(1) of this AD. 

(2) Before or upon the accumulation of 7,000 total flight cycles on any lower frame or reinforcing angle of the main deck cargo door, replace the lower frame or reinforcing angle, as applicable, with new parts. Within 3,000 flight cycles after accomplishment of the replacement, do the HFEC inspection required by paragraph (a)(1) of this AD. 

## Actions Addressing Door Frames or Reinforcing Angles That Have Not Been Replaced 

(b) For airplanes on which any door frame or reinforcing angle at the location where the door latch fittings attach between FS 361.86 and FS 298.12 and WL 202.35 and WL 213.00 has NOT been replaced before the effective date of this AD: Within 1,300 flight cycles after accomplishment of the HFEC inspection required by AD 2000-17-51, amendment 39-11877, do the action specified in either paragraph (b)(1) or (b)(2) of this AD, as applicable, per the Accomplishment Instructions of Pemco Service Bulletin 737-52-0037, Revision 2, dated September 13, 2000, including Attachment 1, dated August 10, 2000. 

(1) For airplanes that have accumulated less than 7,000 total flight cycles since installation of STC SA2969SO: Do an HFEC inspection to detect cracks of the lower frames and reinforcing angles of the main deck cargo door where the door latch fittings attach between FS 361.87 and FS 498.12 and WL 202.35 and WL 213.00. 

(i) If no crack is detected, do the actions specified in paragraphs (b)(1)(i)(A) and (b)(1)(i)(B) of this AD. 

(A) Repeat the HFEC inspection thereafter at intervals of 1,300 flight cycles on the airplane, but not to exceed the accumulation of 7,000 total flight cycles on the airplane. 

(B) Before the accumulation of 7,000 total flight cycles on the airplane, replace the lower frame and reinforcing angle with new parts per the service bulletin. Within 3,000 flight cycles after accomplishment of the replacement, do the HFEC inspection required by paragraph (a)(1) of this AD. 

(ii) If any crack is detected, before further flight, replace the cracked part with a new part having the same part number per the service bulletin. Within 3,000 flight cycles after accomplishment of the replacement, do the HFEC inspection required by paragraph (a)(1) of this AD. 

(2) For airplanes that have accumulated 7,000 or more total flight cycles since installation of STC SA2969SO: Replace the lower frames and reinforcing angles with new parts. Within 3,000 flight cycles after accomplishment of the replacement, do the HFEC inspection required by paragraph (a)(1) of this AD. 

## Alternative Methods of Compliance 

                                (c)(1) 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, Atlanta                                       ( print page 61292)                                    Aircraft Certification Office (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, Atlanta ACO.                             

# Note 2:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Atlanta ACO.

(2) Alternative methods of compliance, approved previously in accordance with AD 2000-17-51, amendment 39-11877, are approved as alternative methods of compliance with the initial HFEC inspection required by paragraph (a)(1) of this AD. 

## Special Flight Permits 

(d) 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 October 11, 2000. 

Donald L. Riggin, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. 

[FR Doc. 00-26595 Filed 10-16-00; 8:45 am] 

BILLING CODE 4910-13-P