01-26712. Airworthiness Directives; Boeing Model 747 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Final rule.

SUMMARY:

This amendment supersedes an existing airworthiness directive (AD), applicable to all Boeing Model 747 series airplanes, that currently requires, for certain airplanes, revising the Airplane Flight Manual, and, for all airplanes, performing repetitive inspections for wear or damage of the inlet check valves and inlet adapters of the override/jettison pumps, and corrective actions, if necessary. This amendment applies to fewer airplanes than the existing AD and requires rework of certain components, which ends the repetitive inspection requirement. These actions are necessary to ensure that the flight crew is advised of the hazards of dry operation of the override/jettison pumps of the center wing fuel tank, and to prevent wear or damage to the inlet check valves and inlet adapters of the override/jettison pumps, which could result in a fire or explosion in the fuel tank during dry (no fuel) operation. This action is intended to address the identified unsafe condition.

DATES:

Effective December 4, 2001.

The incorporation by reference of Boeing Service Bulletin 747-28A2212, Revision 3, dated August 3, 2000, as listed in the regulations, is approved by the Director of the Federal Register as of December 4, 2001.

The incorporation by reference of Boeing Alert Service Bulletin 747-28A2212, Revision 2, dated May 14, 1998, as listed in the regulations, was approved previously by the Director of the Federal Register as of August 24, 1998 (63 FR 42210, August 7, 1998).

ADDRESSES:

The service information referenced in this AD may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. 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:

Sulmo Mariano, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 98-16-19, amendment 39-10695 (63 FR 42210, August 7, 1998), which is applicable to all Boeing Model 747 series airplanes, was published in the Federal Register on February 15, 2000 (66 FR 10393). The action proposed to continue to require, for certain airplanes, revising the Airplane Flight Manual, and, for all airplanes, performing repetitive inspections for wear or damage of the inlet check valves and inlet adapters of the override/jettison pumps, and corrective actions, if necessary. The action also proposed to apply to fewer airplanes than the existing AD and require rework of certain components, which would end the repetitive inspection requirement.

Comments

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

Extend Compliance Time/Delay Terminating Action

Several commenters ask that the compliance time of 18 months after the effective date of the AD, as specified in paragraph (d) of the proposed rule, be extended as follows:

Three commenters state that the compliance time should be extended to within 60 months after the effective date of the AD. One of the commenters asks for an extension to 10,000 flight cycles if a 6-year compliance time is too long. The commenters note that the current repetitive inspections are adequate to address the described unsafe condition by ensuring the integrity of the inlet check valves and override/jettison pump inlet adapters. One commenter adds that the wear limits established and contained in Boeing Alert Service Bulletins 747-28A2212, Revision 1, dated April 23, 1998, and Revision 2, dated May 14, 1998 (referenced in the proposed rule as two of the correct sources of service information for doing the specified actions), are conservative and provide an adequate margin to prevent contact between the inlet check valve and the override/jettison pump inlet inducer/impeller until the modification is accomplished.

Additionally, one commenter (the airplane manufacturer) states that it is not aware of any reports since the issuance of AD 98-16-19, of loosening of the inlet check valve, which is the more significant failure mode per the referenced service bulletin, because it could lead to steel-on-steel contact. AD 98-16-19 requires, among other things, repetitive inspections for wear or damage of the inlet check valves and inlet adapters of the override/jettison pumps. The commenters state that because the unsafe condition in the proposed rule is adequately addressed by the repetitive inspection requirements in that AD, the requested 60-month compliance time is reasonable. This would allow operators to complete the rework of the override/jettison pump housing (installation of the new check valve), which requires fuel tank entry, during a regular maintenance visit when a tank entry is included as part of the maintenance program for most operators. This would minimize the need for multiple tank entries and collateral fuel tank component damage that could result from the entries. An 18-month compliance period would result in unscheduled maintenance visits and increased costs associated with airplane out-of-service time.

The airplane manufacturer also is working with the parts manufacturer to develop an improved override/jettison pump electrical connector that will be proposed as an alternative method of compliance to AD 97-03-17, amendment 39-9922 (62 FR 5748, February 7, 1997). That AD requires an inspection of fuel boost pumps and fuel override/jettison pumps for leakage and checking the electrical resistance of the override/jettison pump wiring insulation. The improved pump electrical connector should be available for retrofit early in the fourth quarter of 2001. A 60-month compliance time would allow the override/jettison pump motor impeller assembly to be reworked during a maintenance visit, at which time both the new inlet adapter and new electrical connector could be installed.

A fourth commenter asks that the compliance time be extended to 54 months after the effective date of the AD to allow for the incorporation of new check valves and inlet adapters in the other airplane fuel tanks, an action not specifically required by this AD, but recommended by the airplane manufacturer. The commenter states that, in the long term, this will prevent the inadvertent installation of an unmodified override/jettison pump in a center wing tank pump housing with a modified inlet check valve, leading to a more rapid failure than is currently occurring. The commenter also states that enhanced endurance testing should be allowed to validate the 30,000 hour wear rate claims and extend that rate to 60,000 hours for the original equipment manufacturer's specified design life limit of the override/jettison pump.

A fifth commenter, the parts manufacturer, states that it is the sole manufacturer of the subject override/jettison pumps, housings, and repair kits and has some constraints on providing the kits, as well as performing the repair and override/jettison pump modification at its overhaul facility. The commenter notes that the maximum monthly production capacity for each kit type is approximately 500 kits per month. All kits are subject to a 12-week lead time following customer order placement. The override/jettison pump overhaul and repair facility can accommodate approximately 200 pump upgrades per month over and above existing pump repair activities. The commenter adds that, in prior discussions with operators, it was noted that the upgrade of the override/jettison pumps on the affected 747 fleet would take up to six years to accomplish. The commenter questions the viability of accomplishing such an upgrade within the proposed 18 months. The commenter states that, although it could deliver the parts required in the time specified, the extensive maintenance tasks necessary to assess and modify the override/jettison pump housings would impose a massive logistics and scheduling burden on the operators.

A sixth commenter states that, due to the spares shortage and possible additional changes in AD 97-03-17, until a final decision is made, it prefers to continue with the repetitive inspections and replacement of any defective override/jettison pumps as required by AD 98-16-19. The commenter notes that after a final decision is made it will comply with all the requirements at one time. The commenter adds that complying with all the requirements at one time will resolve the problems related to spares shortage, long turnaround time for modification by the manufacturer, pump interchangeability, flight schedule interruptions, and extensive ground time.

A seventh commenter asks that the compliance time be extended to 6 years after the effective date of the AD, on the condition that the repetitive inspection interval is reduced to 5,000 flight hours or 1 year. The commenter gives 3 reasons for this extension:

(1) Replacing the housing inlet check valve necessitates entering the center wing fuel tank, which requires a minimum of 2 days of airplane immobilization, and partially prevents concurrent routine maintenance on the airplane.

(2) The parts manufacturer has proposed that operators extend the modification to 6 years so the inside tank modification can be implemented during heavy maintenance. Thus the parts manufacturer can have more time to supply parts for the world fleet.

(3) The parts manufacturer is working with the airplane manufacturer to develop an improved fuel pump electrical connector that will be proposed as an alternative method of compliance to the insulation resistance check required by AD 97-03-17. The commenter asks to be allowed to wait and do all the terminating actions at one time.

The FAA agrees with the commenters that the compliance time required by paragraph (d) of the final rule should be extended somewhat to ensure that enough parts are available to do the required actions within the specified compliance time. In developing an appropriate compliance time for the terminating action required by the final rule, we considered not only the degree of urgency associated with addressing the unsafe condition, but the practical aspect of incorporating the required rework of the existing override/jettison pump housing and impeller motor assembly on the Model 747 fleet in a timely manner. It is our intent in this final rule to have the terminating action done within the time frame of a regular maintenance interval. We took the commenters' recommendations into account, as well as the time necessary to do the specified actions, and we find that a 3-year compliance time should correspond with the regular maintenance schedules of the majority of affected operators. An extension of the compliance time to 3 years will not adversely affect safety because the inspections required by paragraph (b) of the final rule will provide an acceptable level of safety until the terminating action required by paragraph (d) is done. Paragraph (d) of the final rule has been changed accordingly.

The FAA does not agree that the terminating action in this final rule can be delayed in order to do the actions concurrently with AD 97-03-17. These two ADs address different unsafe conditions of the same fuel override/jettison pump, and the associated modifications differ as well. Although the override/jettison pumps for the center wing fuel tank are removed to do the modifications associated with both ADs, the functional tests after installation of the modified pump should identify any problems with the override/jettison pump before the airplane is released for revenue service. Therefore, removing those pumps twice to accomplish the terminating actions for AD 97-03-17 and this AD separately, does not have an adverse effect on the safety of the 747 fleet.

Clarify Wording in Paragraphs (d) and (e)

One commenter asks that paragraphs (d) and (e) of the proposed rule be changed to clarify that the actions are applicable to the center wing tanks only, as specified in the referenced service bulletin. We agree and have changed the wording in paragraphs (d) and (e) of this final rule for clarification.

Change/Delete Paragraph (e)

Two commenters ask that paragraph (e) of the proposed rule; which specifies that, as of the effective date of the AD, no unmodified override/jettison pump housings or impeller motor assemblies may be installed; be changed. The commenter notes that this would require replacement of the override/jettison pump inlet check valve on airplanes not scheduled for maintenance. This would ground airplanes and necessitate a fuel tank entry. The commenter adds that unscheduled fuel tank entries present potential problems with collateral damage and additional out-of-service time for the airplanes. The commenter asks that paragraph (e) be changed to state, “No part number listed in the Existing Part Number column of the table in Paragraph 2.E. of Boeing Service Bulletin 747-28A2212, Revision 3, shall be installed after the effective date of the AD. An existing part number motor impeller assembly can be used on aircraft that have existing part number housings installed, until the sunset date of the AD.”

Another commenter asks that it be allowed to use “Existing Part Numbers” for the center wing tank positions, and for the main 2, main 3, and horizontal stabilizer tank positions during the compliance time specified in the proposed rule. The commenter states that the paragraph (e) of the proposed rule requires a tank entry to modify the override/jettison pump housing each time an unmodified impeller motor assembly has to be replaced.

One commenter, the airplane manufacturer, asks that paragraph (e) of the proposed rule be deleted. The commenter states that the described unsafe condition has been adequately mitigated and that the old parts (with a part number listed in the Existing Part Number column of the table in Paragraph 2.E), should be allowed for installation until the compliance period ends, subject to the limitations described in paragraph 2.E., Existing Parts Accountability, of the referenced service bulletin. The commenter adds that this is necessary for motor impeller assemblies because an operator would install a new inlet check valve in the event a check valve had to be replaced. Installation of a new valve would necessitate installation of a new motor impeller assembly, if not already installed. The commenter notes that once a new part is installed, the replacement part must be of the new configuration.

After careful review of the comments provided, specifically the comment from the airplane manufacturer, the FAA has concluded that paragraph (e) of this final rule should be deleted. We have determined that paragraph (e) can be removed without adversely affecting safety, in that the terminating action specified in Part 5 of the Accomplishment Instructions of Boeing Service Bulletin 747-28A2212, Revision 3, cautions that operators should not install reworked components with non-reworked components because rapid wear of those components will occur. Paragraph (e) of this final rule has been deleted accordingly.

Conclusion

After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

Cost Impact

There are approximately 1,100 airplanes of the affected design in the worldwide fleet. The FAA estimates that 250 airplanes of U.S. registry will be affected by this AD.

For affected airplanes, the AFM revision currently required by AD 98-16-19 takes approximately 1 work hour per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the FAA estimates that the cost impact of this action is $60 per airplane.

The inspections currently required by AD 98-16-19 take approximately 12 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the FAA estimates that the cost impact of this action on U.S. operators is $180,000, or $720 per airplane, per inspection cycle.

The rework required in this AD action will take approximately 6 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will cost approximately $1,978 per airplane. Based on these figures, the FAA estimates that the cost impact of the required replacement on U.S. operators is $584,500, or $2,338 per airplane. The FAA has been advised that manufacturer warranty remedies may be available for labor costs and parts associated with accomplishing the required rework. Therefore, the future economic cost impact of this action on U.S. operators may be less than the cost impact figure indicated above.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the 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.

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

[Amended]

2. Section 39.13 is amended by removing amendment 39-10695 ( 63 FR 42210, August 7, 1998), and by adding a new airworthiness directive (AD), amendment 39-12478, to read as follows:

2001-21-07 Boeing: Amendment 39-12478. Docket 2000-NM-317-AD. Supersedes AD 98-16-19, Amendment 39-10695.

Applicability: Model 747 series airplanes, line numbers 1 through 1251 inclusive, 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 (e)(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 ensure that the flightcrew is advised of the hazards of dry operation of the override/jettison pumps of the center wing fuel tank, and to prevent wear or damage to the inlet check valves and inlet adapters of the override/jettison pumps, which could result in a fire or explosion in the fuel tank during dry operation, accomplish the following:

Restatement of Requirements of AD 98-16-19:

Airplane Flight Manual Revision

(a) For airplanes that have accumulated 20,000 total hours time-in-service or more as of August 24, 1998 (the effective date of AD 98-16-19, amendment 39-10695): Within 14 days after August 24, 1998, revise the Limitations section of the FAA-approved Airplane Flight Manual (AFM) to include the following procedures. This may be accomplished by inserting a copy of this AD into the AFM.

“If the center tank override/jettison fuel pumps are to be used, there must be at least 17,000 pounds (7,720 kilograms) of fuel in the center tank prior to engine start.

Do not operate the center tank override/jettison fuel pumps with less than 7,000 pounds (3,200 kilograms) of fuel in the center tank. For airplanes with an inoperative center tank scavenge system, this 7,000 pounds of center tank fuel must be considered unusable.

If the center tank override/jettison fuel pumps circuit breakers are tripped, do not reset.”

Repetitive Inspections and Corrective Actions

(b) Prior to the accumulation of 10,000 total hours time-in-service, or within 90 days after August 24, 1998, whichever occurs later, accomplish the requirements of paragraphs (b)(1) and (b)(2) of this AD, in accordance with the Accomplishment Instructions specified in Boeing Alert Service Bulletin 747-28A2212, Revision 2, dated May 14, 1998, or Revision 3, dated August 3, 2000.

(1) Perform a detailed visual inspection for wear or damage of the inlet check valve of the left and right override/jettison pumps of the center wing fuel tank.

(i) If the inlet check valve passes all wear and damage criteria, as specified in Figure 3 of the service bulletin, accomplish the actions specified in paragraph (b)(1)(i)(A), (b)(1)(i)(B), or (b)(1)(i)(C) of this AD, as applicable.

(A) If the wear to the stainless steel disk is less than or equal to 0.70 inch, and does not penetrate the disk, repeat the inspection thereafter at intervals not to exceed 10,000 hours time-in-service after the last inspection, until paragraph (d) of this AD has been done.

(B) If the wear to the stainless steel disk is greater than 0.70 inch, and does not penetrate the disk, repeat the inspection thereafter at intervals not to exceed 1,000 hours time-in-service after the last inspection, until paragraph (d) of this AD has been done.

(C) If the wear penetrates the stainless steel disk of the inlet check valve, prior to further flight, accomplish the actions specified in paragraph (b)(1)(ii) of this AD.

(ii) If the inlet check valve fails any wear or damage criteria, as specified in Figure 3 of the service bulletin, prior to further flight, replace the existing check valve with a new or serviceable check valve, in accordance with the service bulletin. Repeat the inspection thereafter at intervals not to exceed 10,000 hours time-in-service after the last inspection, until paragraph (d) of this AD has been done.

(2) Perform a detailed visual inspection for wear or damage of the inlet adapter of the left and right override/jettison pumps of the center wing fuel tank.

(i) If the wear to the inlet adapter is less than or equal to 0.50 inch, prior to further flight, reinstall the existing override/jettison pump, in accordance with the alert service bulletin. Repeat the inspection thereafter at intervals not to exceed 10,000 hours time-in-service after the last inspection, until paragraph (d) of this AD has been done.

(ii) If the wear to the inlet adapter is greater than 0.50 inch, but less than 0.60 inch, prior to further flight, accomplish the actions required by either paragraph (b)(2)(ii)(A) or (b)(2)(ii)(B), in accordance with the service bulletin:

(A) Install a new or serviceable override/jettison pump, and repeat the inspection thereafter at intervals not to exceed 10,000 hours time-in-service after the last inspection, until paragraph (d) of this AD has been done; or

(B) Reinstall the existing override/jettison pump, and repeat the inspection thereafter at intervals not to exceed 1,000 hours time-in-service after the last inspection, until paragraph (d) of this AD has been done.

(iii) If the wear to the inlet adapter is greater than or equal to 0.60 inch, prior to further flight, install a new or serviceable override/jettison pump, in accordance with the service bulletin. Repeat the inspection thereafter at intervals not to exceed 10,000 hours time-in-service after the last inspection, until paragraph (d) of this AD has been done.

Note 2:

Boeing Alert Service Bulletin 747-28A2212, Revision 2, dated May 14, 1998, and Revision 3, dated August 3, 2000, include figures that illustrate specific areas to inspect for wear and damage.

Note 3:

Accomplishment of the actions specified in paragraph (b) of this AD prior to August 24, 1998, in accordance with Revision 1 of Boeing Alert Service Bulletin 747-28A2212, dated April 23, 1998, is considered acceptable for compliance with paragraph (b) of this AD.

Terminating Action for Paragraph (a)

(c) Accomplishment of the actions specified by paragraph (b) of this AD constitutes terminating action for the requirements of paragraph (a) of this AD. Following accomplishment of those actions, the AFM revision may be removed from the AFM.

New Requirements of this AD:

Replacement of Pump Housing and Impeller Motor Assembly

(d) Within 36 months after the effective date of this AD: Rework the existing pump housing and impeller motor assembly, including replacing the existing inlet check valve and inlet adapter in the center wing fuel tank with new, improved parts; in accordance with Boeing Service Bulletin 747-28A2212, Revision 3, dated August 3, 2000. This replacement ends the requirements of paragraphs (a) and (b) of this AD.

Note 4:

Boeing Service Bulletin 747-28A2212, Revision 3, references Crane Hydro-Aire Service Bulletins 60-703-28-33, 60-703-28-35, 60-721-28-5, and 60-723-28-5, as secondary sources of information for the rework of the pump housing and impeller motor assembly.

Alternative Methods of Compliance

(e)(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, Seattle 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, Seattle ACO.

(2) Alternative methods of compliance, approved previously in accordance with AD 98-16-19, amendment 39-10695, are approved as alternative methods of compliance with the corresponding requirements of this AD.

Note 5:

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

Special Flight Permits

(f) 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

(g) Except as provided by paragraph (a) of this AD, the actions shall be done in accordance with Boeing Alert Service Bulletin 747-28A2212, Revision 2, dated May 14, 1998; and Boeing Service Bulletin 747-28A2212, Revision 3, dated August 3, 2000; as applicable.

(1) The incorporation by reference of Boeing Service Bulletin 747-28A2212, Revision 3, dated August 3, 2000, is approved by the Director of the Federal Register as of December 4, 2001.

(2) The incorporation by reference of Boeing Alert Service Bulletin 747-28A2212, Revision 2, dated May 14, 1998, was approved previously by the Director of the Federal Register as of August 24, 1998 (63 FR 42210, August 7, 1998).

(3) Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. 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.

Effective Date

(h) This amendment becomes effective on December 4, 2001.

Issued in Renton, Washington, on October 17, 2001.

Vi L. Lipski,

Manager, Transport Airplane Directorate, Aircraft Certification Service.