2010-29231. Airworthiness Directives; The Boeing Company Model 747 Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Supplemental notice of proposed rulemaking (NPRM); reopening of comment period.

SUMMARY:

We are revising an earlier proposed airworthiness directive (AD) for certain Model 747 airplanes. The original NPRM would have required measuring the electrical bond resistance between the motor operated valve (MOV) actuators and airplane structure for the main, center, auxiliary, and horizontal stabilizer fuel tanks, as applicable, and corrective action if necessary. The original NPRM also would have required a revision to the maintenance program to incorporate airworthiness limitation (AWL) No. 28-AWL-21 or AWL No. 28-AWL-27, as applicable. The original NPRM resulted from fuel system reviews conducted by the manufacturer. This supplemental NPRM would revise the original NPRM by adding airplanes to the applicability, and would require replacing production-installed laminate phenolic spacers with metallic spacers between the fuel jettison MOV and the airplane structure, as applicable. We are proposing this supplemental NPRM to prevent electrical current from flowing through an MOV actuator into a fuel tank, which could create a potential ignition source inside the fuel tank. This condition, in combination with flammable fuel vapors, could result in a fuel tank explosion and consequent loss of the airplane.

DATES:

We must receive comments on this supplemental NPRM by December 14, 2010.

ADDRESSES:

You may send comments by any of the following methods:

• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
• Fax: [phone].
• Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.
• Hand Delivery: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this proposed AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone [phone], extension 1; fax [phone]; e-mail [e-mail]; Internet https://www.myboeingfleet.com. You may review copies of the referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information on the availability of this material at the FAA, call 425-227-1221.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov;​; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Office (telephone [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Douglas Bryant, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2008-0090; Directorate Identifier 2007-NM-312-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD because of those comments.

We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this proposed AD.

Discussion

We issued a notice of proposed rulemaking (NPRM) (the “original NPRM”) to amend 14 CFR part 39 to include an airworthiness directive (AD) that would apply to certain Model 747 airplanes. That original NPRM was published in the Federal Register on January 31, 2008 (73 FR 5773). That original NPRM proposed to require measuring the electrical bond resistance between the motor operated valve (MOV) actuators and airplane structure for the main, center, auxiliary, and horizontal stabilizer fuel tanks, as applicable, and corrective action if necessary. That original NPRM also proposed to require a revision to the maintenance program to incorporate airworthiness limitation (AWL) No. 28-AWL-21 or AWL No. 28-AWL-27, as applicable.

Actions Since Original NPRM Was Issued

Since we issued the original NPRM, we reviewed Boeing Service Bulletin 747-28A2292, Revision 2, dated May 13, 2010 (for Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes). This service bulletin clarifies the procedure for measuring the electrical bond resistance, and adds procedures for replacing production-installed laminate phenolic spacers with metallic spacers for airplanes in Groups 12, 16, 17, 18, and 19. This service bulletin also adds airplanes to the Effectivity. Paragraphs (c) and (g) of this supplemental NPRM have been revised accordingly.

We also reviewed Boeing Service Bulletin 747-28A2294, Revision 1, dated March 5, 2009 (for Model 747-400 series airplanes equipped with an active horizontal stabilizer fuel tank). This service bulletin is the same as the original issue, dated September 21, 2007, except that a reference to Sub-section 28-17-03 of Boeing 747-400 Airplane Maintenance Manual (AMM) is corrected in Revision 1.

We reviewed Boeing 747-100/200/300/SP Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs), Document D6-13747-CMR, Revision March 2008 (hereafter referred to as “Document D6-13747-CMR”). (We referred to Revision January 2007 of Document D6-13747-CMR in the original NPRM.) Document D6-13747-CMR revises certain AWLs for fuel tank systems. However, AWL No. 28-AWL-21, which is specified in this supplemental NPRM, has not been revised in Document D6-13747-CMR, Revision March 2008.

We also reviewed the Boeing 747-400 Maintenance Planning Data (MPD) Document, Section 9, D621U400-9, Revision December 2009 (hereafter referred to as “Boeing 747-400 MPD”). Among other things, Subsection D of Boeing 747-400 MPD has been revised to clarify the “Applicability” of AWL No. 28-AWL-27, which is a critical design configuration control limitation (CDCCL) to maintain the design features of the MOV actuator.

We have revised this supplemental NPRM to refer to the latest service information described previously.

Other Relevant Rulemaking

On April 28, 2008, we issued AD 2008-10-07, Amendment 39-15513 (73 FR 25977, May 8, 2008); and on October 30, 2009, we issued AD 2008-10-07 R1, Amendment 39-16070 (74 FR 56098, November 16, 2009); applicable to all Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes. Those ADs require revising the maintenance program by incorporating new AWLs for fuel tank systems to satisfy Special Federal Aviation Regulation No. 88 (“SFAR 88”) requirements. As an optional action, those ADs also allow incorporating AWL No. 28-AWL-21 into the maintenance program. Therefore, we have added a new paragraph (n) to this supplemental NPRM to specify that incorporating AWL No. 28-AWL-21 into the maintenance program in accordance with paragraph (g) of AD 2008-10-07 or 2008-10-07 R1 terminates the action required by paragraph (k) of this supplemental NPRM for the applicable airplanes.

Comments

We gave the public the opportunity to participate in developing this AD. We considered the comments received from the three commenters.

Request To Allow Use of Future Revisions of the Service Bulletins

Boeing requested that we revise the original NPRM to specify that the proposed modifications may also be done in accordance with any future-approved revisions to Boeing Alert Service Bulletin 747-28A2292, dated September 14, 2007; and Boeing Alert Service Bulletin 747-28A2294, dated September 21, 2007. As justification, Boeing stated that these service bulletins could be revised by the time we issue the AD.

We partially agree. As discussed previously, we have revised this supplemental NPRM to refer to the most recently issued service information. However, we do not agree to refer to “later revisions.” To allow operators to use later revisions of the referenced service documents, either we must revise the AD to reference specific later revisions, or operators must request approval to use later revisions as an alternative method of compliance with the AD. Therefore, we have removed all references to the use of a “later revision” of the applicable service information from this supplemental NPRM to be consistent with FAA policy. We may consider approving the use of later revisions of the service information as an AMOC with this AD, as provided by paragraph (q) of this supplemental NPRM.

Request To Revise Paragraphs (h) and (i) of the Original NPRM

KLM Royal Dutch Airlines (KLM) stated that the intent of the original NPRM is to maintain the design features introduced in accordance with Boeing Alert Service Bulletin 747-28A2292, dated September 14, 2007; and Boeing Alert Service Bulletin 747-28A2294, dated September 21, 2007; respectively; when an MOV actuator is installed. KLM thought that it was clearer if the NPRM stated that the CDCCLs must be incorporated into the applicable paragraphs of the AMM to maintain these design features.

We infer that KLM requests that we revise paragraphs (h) and (i) of the NPRM as proposed above. We disagree with the commenter's request. We disagree that incorporating CDCCLs into the AMM is the appropriate location for a CDCCL. The AMM is not an FAA-approved document. The appropriate location for a CDCCL is in the FAA-approved section (i.e., the Airworthiness Limitations section) of an operator's maintenance program. We have not changed this supplemental NPRM in this regard.

Request To Exclude a Certain Airplane From the Requirements of Paragraph (g) of the Original NPRM

Lufthansa requested that we exclude a certain Model 747-400 series airplane from paragraph (g) of the original NPRM because the horizontal stabilizer tank (HST) on that airplane has never been activated.

We disagree with the request. Although the HST might not be activated at this time, it could be activated in the future. We cannot exclude an airplane from the requirements of this supplemental NPRM without substantiation that the unsafe condition has been adequately addressed. We have not changed this supplemental NPRM in this regard.

Request To Extend Compliance Time

Lufthansa requested that we extend the compliance time of the original NPRM from 60 months to 72 months. Lufthansa stated that this extension will allow operators to implement the modification at the next maintenance layover.

KLM requested that we extend the compliance time of the original NPRM from 60 months to 96 months. KLM stated that tank entry might be necessary for accomplishing the actions, and KLM wanted to avoid tank entry during C-checks.

We disagree with the commenters' requests to extend the compliance time. In developing an appropriate compliance time for this supplemental NPRM, we considered the urgency associated with the subject unsafe condition and the practical aspect of accomplishing the required actions on the Model 747 fleet in a timely manner. We recognize that operators may have different schedules for accomplishing heavy maintenance, but at the same time, we find that the 60-month compliance time will include most operators' schedules for that type of work. Further, according to the provisions of paragraph (q) of this AD, we may consider approving requests to adjust the compliance time if those requests include data that prove that the new compliance time would provide an acceptable level of safety. No change to this supplemental NPRM is necessary in this regard.

Other Change Made to This Supplemental NPRM

We have added a new paragraph (m) to this supplemental NPRM to specify that no alternative CDCCLs may be used unless they are approved as an AMOC. Inclusion of this paragraph in the supplemental NPRM is intended to ensure that the AD-mandated airworthiness limitations changes are treated the same as the airworthiness limitations issued with the original type certificate.

FAA's Determination and Proposed Requirements of the Supplemental NPRM

We are proposing this supplemental NPRM because we evaluated all pertinent information and determined an unsafe condition exists and is likely to exist or develop on other products of the same type design. Certain changes described above expand the scope of the original NPRM. As a result, we have determined that it is necessary to reopen the comment period to provide additional opportunity for the public to comment on this supplemental NPRM.

Explanation of Change to Costs of Compliance

Since issuance of the original NPRM, we have increased the labor rate used in the Costs of Compliance form $80 per work-hour to $85 per work-hour. The Costs of Compliance information, below, reflects this increase in the specified hourly labor rate.

For convenience to the operator, the Estimated Costs table, below, was revised to break out the cost of replacing the spacers and the on-condition costs.

Costs of Compliance

We estimate that this proposed AD will affect 222 airplanes of U.S. registry.

We estimate the following costs to comply with this proposed AD:

Estimated Costs

Action	Labor cost	Parts cost	Cost per product	Cost on U.S. operators
Measurement	Up to 7 work-hours × $85 per hour = Up to $595	Up to $350	Up to $945	Up to $209,790.
Replacement (Up to 60 airplanes)	Up to 4 work-hours × $85 per hour = Up to $340	$1,305	Up to $1,645	Up to $98,700.
Maintenance program revision	1 work-hour × $85 per hour = $85	$0	$85	$18,870.

We estimate the following costs to do any necessary modification that would be required based on the results of the proposed inspection. We have no way of determining the number of aircraft that might need this modification:

On-Condition Costs

Action	Labor cost	Parts cost	Cost per product
Change electrical bond and rework part contact surface	436 work-hours × $85 per hour = $37,060	Up to $35,760	Up to $72,820.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. “Subtitle VII: Aviation Programs,” describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in “Subtitle VII, Part A, Subpart III, Section 44701: General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

Regulatory Findings

We 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 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. 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.

You can find our regulatory evaluation and the estimated costs of compliance in the AD Docket.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Incorporation by reference
• 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.

§ 39.13

[Amended]

2. The FAA amends § 39.13 by adding the following new AD:

The Boeing Company: Docket No. FAA-2008-0090; Directorate Identifier 2007-NM-312-AD.

Comments Due Date

(a) We must receive comments by December 14, 2010.

Affected ADs

(b) None.

Applicability

(c) This AD applies to The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes, certificated in any category; as identified in Boeing Service Bulletin 747-28A2292, Revision 2, dated May 13, 2010.

Note 1:

This AD requires revisions to certain operator maintenance documents to include new inspections. Compliance with these inspections is required by 14 CFR 91.403(c). For airplanes that have been previously modified, altered, or repaired in the areas addressed by these inspections, the operator may not be able to accomplish the inspections described in the revisions. In this situation, to comply with 14 CFR 91.403(c), the operator must request approval for an alternative method of compliance (AMOC) according to paragraph (q) of this AD. The request should include a description of changes to the required inspections that will ensure the continued operational safety of the airplane.

Subject

(d) Air Transport Association (ATA) of America Code 28: Fuel.

Unsafe Condition

(e) This AD results from fuel system reviews conducted by the manufacturer. The Federal Aviation Administration is issuing this AD to prevent electrical current from flowing through a motor operated valve (MOV) actuator into a fuel tank, which could create a potential ignition source inside the fuel tank. This condition, in combination with flammable fuel vapors, could result in a fuel tank explosion and consequent loss of the airplane.

Compliance

(f) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Measurement, Corrective Action, and Replacement

(g) Within 60 months after the effective date of this AD, do the actions required by paragraphs (g)(1) and (g)(2) of this AD, as applicable.

(1) Measure the electrical bond resistance between the MOV actuators and the airplane structure for the main, center, and auxiliary fuel tanks, as applicable; and do all applicable corrective actions; by accomplishing all of the applicable actions in the Accomplishment Instructions of Boeing Service Bulletin 747-28A2292, Revision 2, dated May 13, 2010. The corrective actions must be accomplished before further flight.

(2) For airplanes in Groups 12, 16, 17, 18, and 19, as identified in Boeing Service Bulletin 747-28A2292, Revision 2, dated May 13, 2010: Within 60 months after the effective date of this AD, replace production-installed laminate phenolic spacers with metallic spacers, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-28A2292, Revision 2, dated May 13, 2010.

(h) For airplanes identified in Boeing Service Bulletin 747-28A2294, Revision 1, dated March 5, 2009: Within 60 months after the effective date of this AD, measure the electrical bond resistance between the MOV actuators and airplane structure for the horizontal stabilizer (HST) fuel tanks, and do all the applicable corrective actions, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-28A2294, Revision 1, dated March 5, 2009. The corrective actions must be accomplished before further flight.

Deactivation of the HST

(i) For airplanes identified in Boeing Service Bulletin 747-28A2294, Revision 1, dated March 5, 2009: Deactivation of the HST, in accordance with the applicable Boeing service information specified in Table 1 of this AD, terminates the requirements of paragraph (h) of this AD, except as provided by paragraph (j) of this AD. Deactivation of the HST before the effective date of this AD in accordance with the applicable service information specified in Table 2 of this AD also terminates the requirements of paragraph (h) of this AD, except as provided by paragraph (j) of this AD.

Table 1—Deactivation Service Information

Boeing—	Revision—	Dated—
Service Bulletin 747-28-2265	Original	February 22, 2006.
Service Bulletin 747-28-2272	Original	February 21, 2006.
Service Bulletin 747-28-2274	1	May 21, 2008.
Service Bulletin 747-28-2275	4	February 2, 2009.
Service Bulletin 747-28-2279	2	October 16, 2007.
Service Bulletin 747-28-2285	3	August 30, 2007.
Service Bulletin 747-28-2293	2	March 4, 2008.
Service Bulletin 747-28-2295	2	January 19, 2009.
Service Bulletin 747-28-2296	Original	July 13, 2007.
Service Bulletin 747-28-2300	1	June 2, 2008.
Service Bulletin 747-28-2314	Original	December 9, 2008.

Table 2—Deactivation Credit Service Information

Boeing—	Revision—	Dated—
Service Bulletin 747-28-2274	Original	March 13, 2006.
Service Bulletin 747-28-2275	Original	June 12, 2006.
Service Bulletin 747-28-2275	1	March 16, 2007.
Service Bulletin 747-28-2275	2	July 2, 2007.
Service Bulletin 747-28-2275	3	March 11, 2008.
Service Bulletin 747-28-2279	Original	June 12, 2006.
Service Bulletin 747-28-2279	1	May 25, 2007.
Service Bulletin 747-28-2285	Original	January 23, 2007.
Service Bulletin 747-28-2285	1	May 9, 2007.
Service Bulletin 747-28-2285	2	August 3, 2007.
Service Bulletin 747-28-2293	Original	May 9, 2007.
Service Bulletin 747-28-2293	1	August 29, 2007.
Service Bulletin 747-28-2295	Original	November 17, 2006.
Service Bulletin 747-28-2295	1	March 20, 2008.
Service Bulletin 747-28-2300	Original	January 16, 2008

Reactivation of the HST

(j) For airplanes identified Boeing Service Bulletin 747-28A2294, Revision 1, dated March 5, 2009, on which the HST is reactivated, the HST must be reactivated in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA. For any airplane on which the HST is reactivated, the requirements of paragraphs (h) and (l) of this AD must be done before further flight following the reactivation, or within 60 months after the effective date of this AD, whichever occurs later. For a reactivation method to be approved, the reactivation method must meet the certification basis of the airplane, and the approval must specifically reference this AD.

Maintenance Program Revision

(k) For Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes: Concurrently with accomplishing the actions required by paragraph (g) of this AD, revise the maintenance program by incorporating airworthiness limitation (AWL) No. 28-AWL-21 of Section D of Boeing 747-100/200/300/SP Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs), Document D6-13747-CMR, Revision March 2008.

(l) For Model 747-400, 747-400D, and 747-400F series airplanes: Concurrently with accomplishing the actions required by paragraph (g) of this AD, revise the maintenance program by incorporating AWL No. 28-AWL-27 of Subsection D of Boeing 747-400 Maintenance Planning Data (MPD) Document, Section 9, D621U400-9, Revision December 2009.

No Alternative Critical Design Configuration Control Limitations (CDCCLs)

(m) After accomplishing the applicable action required in paragraph (k) or (l) of this AD, no alternative CDCCLs may be used unless the CDCCLs are approved as an AMOC in accordance with the procedures specified in paragraph (q) of this AD.

Terminating Action for Maintenance Program Revision

(n) For Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes: Incorporating AWL No. 28-AWL-21 into the maintenance program in accordance with paragraph (g) of AD 2008-10-07, Amendment 39-15513; or AD 2008-10-07 R1, Amendment 39-16070; terminates the action required by paragraph (k) of this AD.

Actions Accomplished According to Previous Issue of Service Bulletin

(o) Actions done before the effective date of this AD, in accordance with Boeing Alert Service Bulletin 747-28A2294, dated September 21, 2007, are acceptable for compliance with the corresponding requirements of this AD.

Incorporation of Previous Issues of Airworthiness Limitation (AWL)

(p) Incorporation of AWL No. 28-AWL-21 of Section D of the Boeing 747-100/200/300/SP Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs), Document D6-13747-CMR, Revision January 2007, September 2007, or January 2008, is acceptable for compliance with the corresponding requirements of this AD if done before the effective date of this AD.

Alternative Methods of Compliance (AMOCs)

(q)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Send information to ATTN: Douglas Bryant, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone]. Information may be e-mailed to: [e-mail].

(2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your principal maintenance inspector (PMI) or principal avionics inspector (PAI), as appropriate, or lacking a principal inspector, your local Flight Standards District Office. The AMOC approval letter must specifically reference this AD.

ssued in Renton, Washington on November 10, 2010.

Jeffrey E. Duven,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.