Airworthiness Directives; Boeing Model 747-100, -100B, -100B SUD, -200B, -200C, -300, -400, and -400D Series Airplanes; and Model 747SR Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 747-100, -100B, -100B SUD, -200B, -200C, -300, -400, and -400D series airplanes; and Model 747SR series airplanes. This proposed AD would require repetitive inspections of the forward corner reveals for the main entry door (MED) 3 for cracking, and corrective actions if necessary. This proposed AD is prompted by reports of cracking in the forward corner reveals for the MED 3. We are proposing this AD to detect and correct misalignment of the girt bar fitting due to fatigue failure of the forward corner reveals for MED 3, which could lead to the door escape slide departing from the airplane if the door is opened when the slide is deployed, and consequent injuries to passengers and crew using the door escape slide during an emergency evacuation.

DATES:

We must receive comments on this proposed AD by August 27, 2004.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD.

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., Nassif Building, room PL-401, Washington, DC 20590.
• By fax: (202) 493-2251.
• Hand Delivery: room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

You can get the service information identified in this proposed AD from Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

You may examine the contents of this AD docket on the Internet at http://dms.dot.gov,, or at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., room PL-401, on the plaza level of the Nassif Building, Washington, DC.

FOR FURTHER INFORMATION CONTACT:

Nick Kusz, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6432; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Docket Management System (DMS)

The FAA has implemented new procedures for maintaining AD dockets electronically. As of May 17, 2004, new AD actions are posted on DMS and assigned a docket number. We track each action and assign a corresponding directorate identifier. The DMS AD docket number is in the form “Docket No. FAA-2004-99999.” The Transport Airplane Directorate identifier is in the form “Directorate Identifier 2004-NM-999-AD.” Each DMS AD docket also lists the directorate identifier (“Old Docket Number”) as a cross-reference for searching purposes.

Comments Invited

We invite you to submit any written relevant data, views, or arguments regarding this proposed AD. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2004-18583; Directorate Identifier 2002-NM-285-AD” in the subject line of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments submitted by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov,, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of that website, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov.

We are reviewing the writing style we currently use in regulatory documents. We are interested in your comments on whether the style of this document is clear, and your suggestions to improve the clarity of our communications that affect you. You can get more information about plain language at http://www.faa.gov/language and http://www.plainlanguage.gov.

Examining the Docket

You may examine the AD docket in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the DMS receives them.

Discussion

We have received reports from eight operators indicating that cracking of the lower forward corner reveals for main entry door (MED) 3 was found on Model 747 series airplanes. Of the twelve forward corner reveals that were cracked, eleven were made of cast 356 aluminum and one was made of 6061 aluminum. The cause of the cracking of the forward corner reveals made of cast 356 aluminum is deflection of the airplane structure at the MED 3 frame. The cause of the cracking of the forward corner reveal made of 6061 aluminum was a manufacturing error during the manufacturing process. This condition, if not detected and corrected, could result in misalignment of the girt bar fitting due to fatigue failure of the forward corner reveals for MED 3, which could lead to the door escape slide departing from the airplane if the door is opened when the slide is deployed, and consequent injuries to passengers and crew using the door escape slide during an emergency evacuation.

Explanation of Related AD

We have previously issued AD 96-23-05, amendment 39-9810 (61 FR 58318, November 14, 1996), which applies to certain Boeing Model 747 series airplanes. That AD requires repetitive inspections to detect cracks and/or corrosion of the girt bar support fitting at certain main entry doors, and repair or replacement of the support fitting. That AD also provides for various terminating actions for the repetitive inspections. Inspections, repair, and replacement required by that AD are done in accordance with Boeing Service Bulletin 747-53A2378, Revision 1, dated March 10, 1994. Accomplishment of the applicable repair in this proposed AD would constitute compliance with the requirements of paragraph (k)(2)(ii) of AD 96-23-05 for the repair of the corner casting (reveal) only.

Relevant Service Information

We have reviewed Boeing Special Attention Service Bulletin 747-53-2460, dated June 27, 2002, which describes procedures for performing repetitive detailed inspections of the forward corner reveals for MED 3 for cracking, and follow-on and corrective actions, if necessary. Those actions include the following:

• Performing a material type inspection of the forward corner reveal to determine if it is made of cast 356 aluminum or 6061 aluminum;
• Replacing forward corner reveals with forward corner reveals made of 6061 aluminum;
• Repairing the forward corner reveals (including inspecting for material type and inspecting for cracks); and
• Contacting the manufacturer for repair of forward corner reveals made of 6061 aluminum.

We have determined that accomplishment of the actions specified in the service bulletin will adequately address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other airplanes of this same type design. Therefore, we are proposing this AD, which would require repetitive inspections of the forward corner reveals for the MED 3 for cracking, and corrective actions if necessary. The proposed AD would require you to use the service information described previously to perform these actions, except as discussed under “Differences Between the Proposed AD and the Service Bulletin.”

Differences Between the Proposed AD and the Service Bulletin

Operators should note that, although the service bulletin specifies that, if the forward corner reveal is found to be made from 6061 aluminum or if a new 6061 aluminum corner reveal is installed, no further action is necessary, this proposed AD would require repetitive inspections if the forward corner reveal is made of 6061 aluminum. The cracking that was found in a forward corner reveal made of 6061 aluminum, as discussed previously, was detected after the service bulletin was issued. Therefore, we determined that all forward corner reveals need to be repetitively inspected to adequately ensure continued operational safety.

In addition, operators should note that, although the service bulletin does not specify coordinating with the manufacturer if the repair of a forward corner reveal consists of installing a new forward corner reveal made of 6061 aluminum, operators must coordinate with the manufacturer to ensure that the new forward corner reveal is free from manufacturing defects before obtaining FAA approval for the repair.

Although Figure 1 of the service bulletin says to “repeat inspections every 3,000 flight-cycles” and to “perform the next inspection prior to 3,000 flight-cycles,” this proposed AD requires repetitive inspections at intervals not to exceed 3,000 flight cycles for forward corner reveals made of cast 356 aluminum and repetitive inspections at intervals not to exceed 1,500 flight cycles for forward corner reveals made of 6061 aluminum.

Operators should also note that, while Boeing Special Attention Service Bulletin 747-53-2460, dated June 27, 2002, specifies the effectivity to be “all 747 airplanes line numbers 1 through 1037 except for 747-SP's, Freighters and airplanes converted to Special Freighters,” this proposed AD has an applicability of “Model 747-100, -100B, -100B SUD, -200B, -200C, -300, -400, and -400D series airplanes; and Model 747SR series airplanes, line numbers 1 through 1,342 inclusive, except freighters and airplanes converted to Boeing special freighters.” The line numbers were changed to include airplanes with forward corner reveals made of 6061 aluminum that may have a manufacturing defect. It has been verified that airplanes with line number 1343 and up have forward corner reveals installed that are made from 6061 aluminum and do not have the manufacturing defect.

Also operators should note that Figure 1 of the service bulletin specifies the initial inspection threshold to be “At or prior to 7,000 flight-cycles, or within 2,000 flight-cycles of the issue date of this service bulletin, or within 3,000 flight-cycles of the last inspection of the door 3 corner reveal as given in Boeing Service Bulletin 747-53A2378, whichever is later.” However, this proposed AD would require the initial inspection within 1,500 flight cycles after the effective date of the AD. We have determined that the threshold listed in Figure 1 of the service bulletin would not address the identified unsafe condition soon enough to ensure an adequate level of safety for the affected fleet. In developing an appropriate compliance time for this AD, we considered new reports since the service bulletin was issued, the manufacturer's recommendation and the degree of urgency associated with the subject unsafe condition. In light of all of these factors, we find that requiring the initial inspection within 1,500 flight cycles represents an appropriate interval of time for affected airplanes to continue to operate without compromising safety.

In addition, although the service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, this proposal would require the repair of those conditions to be accomplished per a method approved by the FAA, or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the FAA to make those findings.

Furthermore, although step 5 of Figure 8 of the service bulletin specifies that operators may accomplish the actions on forward corner reveals made of cast 356 aluminum in accordance with “an operator's equivalent procedure,” this proposed AD would require operators to accomplish step 5 of Figure 8 only in accordance with the procedures specified in Standard Overhaul Practices Manual (SOPM) 20-20-02. An “operator's equivalent procedure” may be used only if approved as an alternative method of compliance in accordance with paragraph (m) of this AD.

The differences described above have been coordinated with the manufacturer.

Costs of Compliance

This proposed AD would affect about 146 airplanes of U.S. registry and 926 airplanes worldwide. The proposed detailed inspection for cracking would take about 1 work hour per airplane, at an average labor rate of $65 per work hour. Based on these figures, the estimated cost of the proposed AD for U.S. operators is $9,490, or $65 per airplane, per inspection cycle.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD 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.

For the reasons discussed above, I certify that the 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. 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.

We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD. See the ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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.