Airworthiness Directives; The Boeing Company Airplanes

[Federal Register Volume 86, Number 55 (Wednesday, March 24, 2021)]
[Rules and Regulations]
[Pages 15572-15575]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-06023]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0785; Product Identifier 2020-NM-063-AD; Amendment 
39-21477; AD 2021-06-10]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all 
The Boeing Company Model 747 series airplanes and Model 767 series 
airplanes. This AD was prompted by a report of an un-commanded fuel 
transfer between the main and center fuel tanks. This AD prohibits 
operation of an airplane with any inoperative refuel valve (fueling 
shut-off valve) failed in the open position. The FAA is issuing this AD 
to address the unsafe condition on these products.

DATES: This AD is effective April 28, 2021.

ADDRESSES:

Examining the AD Docket

    You may examine the AD docket on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2020-
0785; or in person at Docket Operations between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays. The AD docket contains 
this final rule, any comments received, and other information. The 
address for Docket Operations is U.S. Department of Transportation, 
Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 
New Jersey Avenue SE, Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Douglas Mansell, Aerospace Engineer, 
Propulsion Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des 
Moines, WA 98190; phone and fax: 206-231-3875; email: 
[email protected].

SUPPLEMENTARY INFORMATION:

Background

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 by adding an AD that would apply to all The Boeing Company 
Model 747 series airplanes and Model 767 series airplanes. The NPRM 
published in the Federal Register on September 9, 2020 (85 FR 55622). 
The NPRM was prompted by a report of an un-commanded fuel transfer 
between the main and center fuel tanks. The NPRM proposed to prohibit 
operation of an airplane with any inoperative refuel valve (fueling 
shut-off valve) failed in the open position.
    The FAA is issuing this AD to address multiple refuel valves failed 
in the ``open'' position via Master Minimum Equipment List (MMEL) 
dispatch allowance, which allows un-commanded fuel transfer between 
fuel tanks. This condition could result in a fuel exhaustion event.

Comments

    The FAA gave the public the opportunity to participate in 
developing this final rule. The following presents the comments 
received on the NPRM and the FAA's response to each comment.

Support for the NPRM

    United Airlines had no objection to the NPRM. Another commenter 
stated that the NPRM was justified.

Request To Identify Proposed AD as Interim Action

    Boeing requested that the proposed AD be identified as interim 
action because it is working on an updated MMEL to provide modified 
dispatch relief.
    The FAA agrees with the commenter's request for the reason provided 
by the commenter. The FAA has revised the preamble in this final rule 
to identify this AD as interim action.

Request To Clarify Certain Terminology

    Boeing requested that throughout the proposed AD the word 
``secured'' be changed to ``failed'' when referring to the fuel shutoff 
valves. The commenter explained that the Minimum Equipment List (MEL) 
does not direct operators to secure the fuel shutoff valve open; the 
MEL states that operators are allowed to operate (dispatch) an airplane 
with a

[[Page 15573]]

valve failed (inoperative) in the open position.
    The FAA agrees with the commenter's request for the reasons 
provided by the commenter. The FAA has accordingly revised the 
description of the unsafe condition and AD requirements in the SUMMARY 
and Background sections of this final rule, and in paragraphs (e) and 
(g) of this AD.

Request for Clarification Regarding Revisions to MMEL Items for Model 
747SP Series Airplanes

    A commenter requested clarification regarding revisions to MMEL 
items for Model 747SP series airplanes. The commenter stated the 
company he is affiliated with operates two Model 747SP series airplanes 
and asked if the final instruction would require eliminating ATA 28-20 
(2) through (6) from its MEL, or if those sections would be revised 
with different maintenance instructions, which would allow dispatching 
an airplane with only one inoperative refueling valve deactivated in 
the open position, or if there would be a revision to those sections 
with different maintenance instructions allowing dispatching an 
airplane with inoperative refueling valves deactivated in the closed 
position (for example, if the refueling valves could be manually opened 
on the ground for re-fueling and then closed for flight if only the 
valve's actuator is defective).
    The FAA provides the following explanations to the commenter's 
questions. This AD eliminates the relief provided by the dispatch 
provisions of ATA 28-20 (2), (3), (4), (5), and (6) from the Boeing 747 
B-747-100/200/300/SP SERIES MMEL. This AD therefore prohibits dispatch 
of an airplane with any of the subject refuel valves inoperative in the 
open position, regardless of the existence of any MMEL provisions. If 
the MMEL items are revised in the future, the FAA might issue global 
AMOCs to provide relief for operation under specified conditions. This 
AD does not change the MMEL dispatch provisions for refuel valves 
inoperative in the closed position.

Request To Reduce the Compliance Time

    The Air Line Pilots Association, International (ALPA) requested 
that the compliance time specified in the proposed AD be reduced from 
60 days after the effective date of the AD to 15 days. The commenter 
stated that operators have had sufficient time from the publication 
date of the proposed AD (September 9, 2020) until the publication date 
of the final rule to address the prohibition of dispatching airplanes 
with more than one affected refuel valve inoperative.
    The FAA disagrees with the commenter's request. After considering 
all of the available information, the FAA determined that the 
compliance time, as proposed, represents an appropriate interval of 
time for operators to comply with the AD, and still maintain an 
adequate level of safety. In developing an appropriate compliance time, 
the FAA considered the safety implications of operating an airplane 
with any inoperative refuel valve. In addition, reducing the compliance 
time of the proposed AD would necessitate (under the provisions of the 
Administrative Procedure Act) reissuing the notice, reopening the 
period for public comment, considering additional comments subsequently 
received, and eventually issuing a final rule. That procedure could add 
unwarranted time to the rulemaking process. In light of this, and in 
consideration of the amount of time that has already elapsed since 
issuance of the original notice, the FAA determined that further delay 
of this AD is not appropriate. However, if additional data are 
presented that would justify a shorter compliance time, the FAA may 
consider further rulemaking on this issue. The FAA has not revised this 
AD in regard to this issue.

Request To Include MMEL Item for Model 747-8 Passenger Airplanes

    Boeing and AMES Sarl (CAMO) requested that MMEL Item 28-21-02-01A, 
``Refuel Valves,'' which applies to passenger airplanes, be included in 
paragraph (h)(4) of the proposed AD. The commenters noted that in 
paragraph (h)(4) of the proposed AD, only MMEL Item 28-21-01-01A, 
``Refuel Valves,'' is specified, and that MMEL item is applicable only 
to Model 747-8F airplanes, which are freighter airplanes.
    The FAA agrees with the commenters' requests for the reasons 
provided by the commenters and has revised paragraph (h)(4) of this AD 
accordingly.

Request To Remove Reference to MMEL Items for Model 767-2C Series 
Airplanes

    Boeing requested that MMEL items referring to Model 767-2C series 
airplanes be removed from paragraph (h)(6) of the proposed AD because 
an FAA-approved MMEL document does not exist for this model. The 
commenter explained that only a Dispatch Deviation Guide (DDG) has been 
issued for Model 767-2C series airplanes and that the MMEL items 
referenced in paragraphs (h)(6)(i) and (ii) of the proposed AD are 
found only in the DDG and are not public documents; therefore it is not 
appropriate to reference these MMEL items in the proposed AD.
    The FAA agrees with the commenter's request for the reasons 
provided by the commenter. The FAA has removed paragraph (h)(6) of this 
AD because there is no published MMEL for Model 767-2C series 
airplanes.

Request To Remove References to Model KC-46A Airplanes

    Boeing requested that all text referring to Model KC-46A airplanes 
be removed from the NPRM. The commenter explained that for type 
certification purposes, Model KC-46A airplanes are covered under the 
type certificate for Model 767-2C series airplanes.
    The FAA agrees with the commenter's request for the reason provided 
by the commenter. As stated previously, paragraph (h)(6) of the 
proposed AD, which provided MMEL information for Model 767-2C 
airplanes, has been removed from this AD.

Request for Clarification of Affected Fuel Tanks in Paragraph (g) of 
the Proposed AD

    Boeing requested that paragraph (g) of the proposed AD be revised 
to clarify which fuel tanks are affected. The commenter stated that the 
identified unsafe condition is not evident when an airplane is 
operating using the existing DDG and MMEL relief for fuel tanks with 
refuel valves that are isolated from the main manifold that provides 
fuel to the wing tanks. The commenter explained that the fuel tanks 
that are not affected include the auxiliary tanks and the horizontal 
stabilizer tank on Model 747 series airplanes and the body fuel tanks 
on Model 767-2C series airplanes.
    The FAA agrees with the commenter's request. The FAA has determined 
that this clarification could reduce confusion among operators 
regarding which fuel tanks are affected by the unsafe condition 
identified in this AD. The FAA has revised this final rule to clarify 
that this AD prohibits operation of an airplane with any inoperative 
refuel valve (fueling shut-off valve) of ``the reserve tank (on Model 
747 series airplanes), main tank, or center tank'' that has failed in 
the open position.

Request To Revise Paragraph (g) of the Proposed AD To Prohibit Dispatch 
if More Than One Refuel Valve Is Inoperative

    United Parcel Service (UPS Airlines) requested that paragraph (g) 
of the proposed AD be revised to specify that dispatch of an airplane 
is allowed if there is only one inoperative refuel valve. The commenter 
agreed that if

[[Page 15574]]

multiple refuel valves were secured in the open position there could be 
an un-commanded fuel transfer between fuel tanks. The commenter 
explained that a review of the fuel control systems on its fleet 
revealed that the fuel transfer would occur only if two valves were 
open, each in a different tank. The commenter noted that if only one 
valve was secured (failed) open, fuel could enter the manifold but 
could not migrate into a different tank. The commenter stated that it 
had contacted Boeing regarding dispatch of an airplane with one refuel 
valve secured in the open position and that Boeing stated this provides 
an acceptable level of safety to the proposed AD. The commenter 
explained that Boeing is developing substantiating analysis to support 
dispatch of an airplane with one refuel valve secured in the open 
position for many of the affected airplane models.
    In addition, the commenter requested that the repair category be 
specified as category B (three day deferral) because the replacement of 
a refuel valve, which involves fuel tank access and requires 
specialized training and additional time to properly vent the fuel 
tanks, would place an undue burden on operators when another acceptable 
alternative is available.
    The FAA does not agree with the commenter's requests. The FAA has 
determined that the operational limitations imposed by this AD are 
warranted, and adequately address the unsafe condition. Boeing has not 
yet finalized or provided the FAA with its substantiating analysis to 
support dispatch of an airplane with one refuel valve secured in the 
open position. Boeing has indicated that in the future it might provide 
updates for the applicable DDG and MMEL for each affected airplane 
model to provide modified dispatch relief. The FAA has not revised this 
AD in regard to this issue.

Request To Revise Paragraph (h) of the Proposed AD To Refer to MEL 
Instead of MMEL

    Boeing requested that the header for paragraph (h) in the proposed 
AD be changed from MMEL Items to MEL Items. The commenter also 
requested that paragraphs (h)(1) through (6) be revised to refer to MEL 
items instead of MMEL items. The commenter stated that these changes 
would provide clarification that MEL(s) would be updated and the 
wording would be consistent with that of similar ADs.
    The FAA partially agrees with the commenter's requests. The FAA 
agrees with the commenter's statement that operators will need to 
update their MELs to comply with the change required by this AD. 
Because dispatch requirements have changed for the applicable airplane 
models, the FAA disagrees with removing the reference to the identified 
MMEL items because this AD does not mandate the actual change to the 
applicable MMEL. This AD identifies which FAA-approved MMEL items are 
affected. Operators consult the MMEL requirements when updating the 
operator's existing FAA-approved MEL. The FAA has revised paragraph (h) 
of this AD accordingly.

Request To Include Note 2 to Paragraph (h) of the Proposed AD

    Boeing requested that Note 2 be added to paragraph (h) of the 
proposed AD stating that operators must not dispatch an airplane using 
MMEL Item 28-21-01 with any of the identified valves in the inoperative 
open condition. The commenter explained that this would prevent 
dispatch of an airplane with fueling shutoff valves in the inoperative 
open condition without requiring a reference to a specific chapter of 
the MMEL.
    The FAA disagrees with the commenter's request. Not all affected 
airplanes have MMEL items in section 28-21. Further, the intent of the 
commenter's proposed text is adequately addressed in the provisions of 
paragraph (g) of this AD, which is unchanged from the proposed AD. The 
FAA has not changed this AD as a result of this comment.

Conclusion

    The FAA reviewed the relevant data, considered the comments 
received, and determined that air safety and the public interest 
require adopting this final rule with the changes described previously 
and minor editorial changes. The FAA has determined that these minor 
changes:
    <bullet> Are consistent with the intent that was proposed in the 
NPRM for addressing the unsafe condition; and
    <bullet> Do not add any additional burden upon the public than was 
already proposed in the NPRM.
    The FAA also determined that these changes will not increase the 
economic burden on any operator or increase the scope of this final 
rule.

MMEL Revisions

    This AD refers to items in Sections 28-20 and 28-21 of the MMEL; 
\1\ those items may also be included in an operator's FAA-approved MEL. 
This AD prohibits operation of the airplane under conditions currently 
allowed by those items in the MMEL. The FAA plans to revise the MMEL to 
remove those items in a future revision; operators would then be 
required to also remove those items from their existing FAA-approved 
MEL.
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    \1\ The MMEL items can be found in the applicable FAA-approved 
MMEL: Boeing 747 B-747-100/200/300/SP SERIES MMEL, Revision 35, 
dated April 25, 2014; Boeing 747 B-747-400 LCF MMEL, Revision 3, 
November 7, 2014; Boeing 747 B-747-400, B-747-400D, B-747-400F MMEL, 
Revision 32, dated December 27, 2018; Boeing 747-8 MMEL, Revision 7, 
dated August 25, 2017; and Boeing 767 MMEL, Revision 39, dated 
October 26, 2018; which can be found on the Flight Standards 
Information Management System (FSIMS) website, https://fsims.faa.gov/PICResults.aspx?mode=Publication&doctype=MMELByModel.
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Interim Action

    The FAA considers this AD interim action. The manufacturer is 
currently developing an updated MMEL, with substantiation, that would 
allow limited relief for an inoperative open fuel shutoff valve and 
mitigate the unsafe condition. Once the updated MMEL is developed, 
approved, and available, the FAA might consider additional rulemaking.

Costs of Compliance

    The FAA estimates that this AD affects 750 airplanes of U.S. 
registry.
    The FAA has determined that revising the operator's existing FAA-
approved MEL takes an average of 90 work-hours per operator, although 
the agency recognizes that this number may vary from operator to 
operator. Since operators typically incorporate MEL changes for their 
affected fleet(s), the FAA has determined that a per-operator estimate 
is more accurate than a per-airplane estimate. Therefore, the FAA 
estimates the average total cost per operator to be $7,650 (90 work-
hours x $85 per work-hour).

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.
    The FAA is 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

[[Page 15575]]

unsafe condition that is likely to exist or develop on products 
identified in this rulemaking action.

Regulatory Findings

    This AD will not have federalism implications under Executive Order 
13132. This AD 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.
    For the reasons discussed above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Will not affect intrastate aviation in Alaska, 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.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive:

2021-06-10 The Boeing Company: Amendment 39-21477; Docket No. FAA-
2020-0785; Product Identifier 2020-NM-063-AD.

(a) Effective Date

    This airworthiness directive (AD) is effective April 28, 2021.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to all The Boeing Company airplanes, 
certificated in any category, identified in paragraphs (c)(1) and 
(2) of this AD.
    (1) Model 747-100, -100B, -100B SUD, -200B, -200C, -200F, -300, 
-400, -400D, -400F, 747SR, 747SP, -8F, and -8 series airplanes.
    (2) Model 767-200, -300, -300F, -400ER, and -2C series 
airplanes.

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by a report of an un-commanded fuel 
transfer between the main and center fuel tanks. The FAA is issuing 
this AD to address multiple refuel valves failed in the ``open'' 
position via Master Minimum Equipment List (MMEL) dispatch 
allowance, which allows un-commanded fuel transfer between fuel 
tanks. This condition could result in a fuel exhaustion event.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Conditions for Prohibited Operation

    No later than 60 days after the effective date of this AD: 
Operation of an airplane with any inoperative refuel valve (fueling 
shut-off valve) of the reserve tank (on Model 747 series airplanes 
only), main tank, or center tank that has failed in the open 
position is prohibited.

(h) Minimum Equipment List (MEL) Items

    The MMEL items specified in paragraphs (h)(1) through (5) of 
this AD are affected by this prohibition and therefore may affect 
the operator's FAA-approved MEL.
    (1) For Model 747-100, -200, and -300 series airplanes: The 
following ``Pressure Fueling System'' items.
    (i) MMEL Item 28-20 2), ``Main Tank 1 and 4 Refueling Valves.''
    (ii) MMEL Item 28-20 3), ``Main Tank 2 and 3 Refueling Valves.''
    (iii) MMEL Item 28-20 4), ``Center Tank Refueling Valves.''
    (iv) MMEL Item 28-20 5), ``Reserve Tank 1 and 4 Refueling 
Valves.''
    (v) MMEL Item 28-20 6), ``Reserve Tank 2 and 3 Refueling 
Valves.''
    (2) For Model 747-400LCF series airplanes: MMEL Item 28-21-1 1), 
``Refuel Valves,'' second dispatch case with refueling valves 
inoperative open.
    (3) For Model 747-400 series airplanes: MMEL Item 28-21-1 1), 
``Refuel Valves,'' first dispatch case with refueling valves 
inoperative open.
    (4) For Model 747-8 series airplanes: The following ``Refuel 
Valves'' items.
    (i) MMEL Item 28-21-01-01-01A, ``Refuel Valves.''
    (ii) MMEL Item 28-21-01-02-01A, ``Refuel Valves.''
    (5) For Model 767 series airplanes (except Model 767-2C 
airplanes, for which there is no published MMEL): MMEL Item 28-21-
01-01B, ``Fuel Shutoff Valves.''
    Note 1 to paragraph (h): The MMEL items specified in paragraph 
(h) of this AD can be found in the applicable FAA-approved MMEL: 
Boeing 747 B-747-100/200/300/SP SERIES MMEL, Revision 35, dated 
April 25, 2014; Boeing 747 B-747-400 LCF MMEL, Revision 3, November 
7, 2014; Boeing 747 B-747-400, B-747-400D, B-747-400F MMEL, Revision 
32, dated December 27, 2018; Boeing 747-8 MMEL, Revision 7, dated 
August 25, 2017; and Boeing 767 MMEL, Revision 39, dated October 26, 
2018; which can be found on the Flight Standards Information 
Management System (FSIMS) website, https://fsims.faa.gov/PICResults.aspx?mode=Publication&doctype=MMELByModel.

(i) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Seattle ACO Branch, FAA, has the authority to 
approve AMOCs for this AD, if requested using the procedures found 
in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request 
to your principal inspector or local Flight Standards District 
Office, as appropriate. If sending information directly to the 
manager of the certification office, send it to the attention of the 
person identified in paragraph (j) of this AD. Information may be 
emailed to: [email protected].
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.
    (3) An AMOC that provides an acceptable level of safety may be 
used for any repair, modification, or alteration required by this AD 
if it is approved by The Boeing Company Organization Designation 
Authorization (ODA) that has been authorized by the Manager, Seattle 
ACO Branch, FAA, to make those findings. To be approved, the repair 
method, modification deviation, or alteration deviation must meet 
the certification basis of the airplane, and the approval must 
specifically refer to this AD.

(j) Related Information

    For more information about this AD, contact Douglas Mansell, 
Aerospace Engineer, Propulsion Section, FAA, Seattle ACO Branch, 
2200 South 216th St., Des Moines, WA 98190; phone and fax: 206-231-
3875; email: [email protected].

(k) Material Incorporated by Reference

    None.

    Issued on March 12, 2021.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2021-06023 Filed 3-23-21; 8:45 am]
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