Document ID: FAA-2021-0962-0001
Agency: faa
Document Type: Proposed Rule
Title: Airworthiness Directives: The Boeing Company Airplanes
Posted Date: 2021-12-28T05:00Z

[Federal Register Volume 86, Number 246 (Tuesday, December 28, 2021)]
[Proposed Rules]
[Pages 73712-73715]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-27838]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0962; Project Identifier AD-2021-00997-T]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain The Boeing Company Model 777-200 and -300 series airplanes. 
This proposed AD was prompted by reports of three incidents involving 
in-flight fan blade failures on certain Pratt & Whitney engines (``fan 
blades'' are also known as ``1st-stage low-pressure compressor (LPC) 
blades''--these terms are used interchangeably in this proposed AD). 
This proposed AD would require installation of debris shields on the 
thrust reverser (T/R) inner wall at the left and right sides of the 
lower bifurcation, inspection of the fan cowl doors for moisture 
ingression, repetitive functional checks of the hydraulic pump shutoff 
valves to ensure they close in response to the fire handle input, and 
corrective actions if necessary. The FAA is proposing this AD to 
address the unsafe condition on these products.

DATES: The FAA must receive comments on this proposed AD by January 27, 
2022.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:
     Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     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: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    For Boeing service information identified in this NPRM, contact 
Boeing Commercial Airplanes, Attention: Contractual & Data Services 
(C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740-5600; 
telephone 562-797-1717; internet https://www.myboeingfleet.com. For 
Pratt & Whitney service information identified in this NPRM contact 
Pratt & Whitney Division, 400 Main Street, East Hartford, CT 06118; 
phone: 860-565-0140; email: [email protected]; website: https://connect.prattwhitney.com. You may view this service information at the 
FAA, Airworthiness Products Section, Operational Safety Branch, 2200 
South 216th St., Des Moines, WA. For information on the availability of 
this material at the FAA, call 206-231-3195.

Examining the AD Docket

    You may examine the AD docket at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2021-0962; 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 NPRM, any comments 
received, and other information. The street address for Docket 
Operations is listed above.

FOR FURTHER INFORMATION CONTACT: James Laubaugh, Aerospace Engineer, 
Propulsion Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des 
Moines, WA 98198; phone and fax: 206-231-3622; email: 
[email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA invites you to send any written relevant data, views, or 
arguments about this proposal. Send your comments to an address listed 
under ADDRESSES. Include ``Docket No. FAA-2021-0962; Project Identifier 
AD-2021-00997-T'' at the beginning of your comments. The most helpful 
comments reference a specific portion of the proposal, explain the 
reason for any recommended change, and include

[[Page 73713]]

supporting data. The FAA will consider all comments received by the 
closing date and may amend this proposal because of those comments.
    Except for Confidential Business Information (CBI) as described in 
the following paragraph, and other information as described in 14 CFR 
11.35, the FAA will post all comments received, without change, to 
https://www.regulations.gov, including any personal information you 
provide. The agency will also post a report summarizing each 
substantive verbal contact received about this NPRM.

Confidential Business Information

    CBI is commercial or financial information that is both customarily 
and actually treated as private by its owner. Under the Freedom of 
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public 
disclosure. If your comments responsive to this NPRM contain commercial 
or financial information that is customarily treated as private, that 
you actually treat as private, and that is relevant or responsive to 
this NPRM, it is important that you clearly designate the submitted 
comments as CBI. Please mark each page of your submission containing 
CBI as ``PROPIN.'' The FAA will treat such marked submissions as 
confidential under the FOIA, and they will not be placed in the public 
docket of this NPRM. Submissions containing CBI should be sent to James 
Laubaugh, Aerospace Engineer, Propulsion Section, FAA, Seattle ACO 
Branch, 2200 South 216th St., Des Moines, WA 98198; phone and fax: 206-
231-3622; email: [email protected]. Any commentary that the FAA 
receives which is not specifically designated as CBI will be placed in 
the public docket for this rulemaking.

Background

    The FAA has received reports of three incidents involving in-flight 
fan blade failures and shutdowns on certain The Boeing Company Model 
777-200 and 777-300 series airplanes equipped with Pratt & Whitney 
(P&W) Model PW4000 series turbofan engines. The two most recent events 
occurred in December 2020 and February 2021. In the latter incident, 
the engine fan blade failure occurred during climb at approximately 
13,000 feet. While the engine fan blade failure was contained by the 
fan case, the event loads caused structural failures that resulted in 
the inlet (inlet lip, inner and outer barrel, and aft bulkhead) and fan 
cowl doors separating from the engine and airplane. The resultant 
separated engine and nacelle parts caused damage to the wing and 
fuselage. Several flammable fluid lines, the engine accessory gearbox, 
and T/R structure were fractured. The hydraulic pump shutoff valve 
failed to close when the fire handle was pulled, contributing 
additional flammable fluid to the engine nacelle and T/R resulting in 
an uncontained engine fire.
    In the December 2020 incident, the engine fan blade failure 
occurred during climb at approximately 15,000 feet. While the engine 
fan blade failure was contained by the fan case, the event loads caused 
structural failures that resulted in the fan cowl doors separating from 
the engine and airplane. The resultant separated engine and nacelle 
parts caused damage to the left side horizontal stabilizer and 
fuselage. The engine accessory gearbox and T/R attachment to the engine 
were also fractured.
    In the earliest incident, which occurred in 2018, the engine fan 
blade failure occurred just after beginning the descent. While the 
engine fan blade failure was contained by the fan case, the event loads 
caused structural failures that resulted in the inlet (inlet lip, inner 
and outer barrel, and aft bulkhead) and fan cowl doors separating from 
the engine and airplane. The resultant separated engine and nacelle 
parts caused damage to the right side horizontal stabilizer, wing and 
fuselage.
    Upon the occurrence of the February 2021 in-flight engine fan blade 
failure, the FAA issued Emergency AD 2021-05-51, Amendment 39-21470 (86 
FR 13445, March 9, 2021) requiring inspection of the engine fan blades 
for cracking and removal from service if any cracking is found. Since 
the two most recent incidents and issuance of that Emergency AD, the 
FAA, Boeing, and P&W have continued to examine the airplane and engine 
design, along with the information provided through the incident 
investigations, to determine if further action is necessary. The FAA 
has determined that further action is necessary to address the 
airplane-level implications and unsafe condition resulting from in-
flight engine fan blade failures. Fan blade failures can cause fan 
rotor imbalance and result in fan blade fragments penetrating the inner 
and outer barrel of the inlet. This condition, if not addressed, could 
result in the separation of inlet and fan cowl doors and the T/R cowl. 
This could lead to engine in-flight shutdown, impact damage to the 
empennage, with significantly increased aerodynamic drag causing fuel 
exhaustion or the inability to maintain altitude during operations 
under extended-range twin-engine operational performance standards 
(ETOPS) missions, and uncontrolled engine fire, which could result in 
loss of control of the airplane, a forced off-airport landing, and 
injury to passengers.

FAA's Determination

    The FAA is issuing this NPRM after determining that the unsafe 
condition described previously is likely to exist or develop on other 
products of the same type design.

Related Service Information Under 1 CFR part 51

    The FAA reviewed Pratt & Whitney Alert Service Bulletin PW4G-112-
A72-361, dated October 15, 2021. This service information specifies 
procedures for performing thermal acoustic image and ultrasonic testing 
inspections of 1st-stage LPC blades. This service information is 
reasonably available because the interested parties have access to it 
through their normal course of business or by the means identified in 
ADDRESSES.

Related Service Information

    The FAA reviewed Subtasks 26-21-00-200-018, 26-21-00-200-019, and 
26-21-00-840-022, of Boeing 777-200/300 Aircraft Maintenance Manual, 
dated September 5, 2021. The service information specifies procedures 
for performing a functional check of the engine-driven pump shutoff 
valve.

Proposed AD Requirements in This NPRM

    This proposed AD would require doing the following actions in 
accordance with a method approved by the Manager, Seattle ACO Branch, 
FAA.
     Installing debris shields on the T/R inner wall at the 
left and right sides of the lower bifurcation.
     Inspecting the fan cowl doors for moisture ingression and 
corrective action (i.e., repair) if necessary.
     Repetitive functional checks of the hydraulic pump shutoff 
valves to ensure they close in response to the fire handle input, and 
corrective actions (i.e., repair) if necessary.

Explanation of Special Flight Permit Paragraph

    This proposed AD is related to NPRM Docket Number FAA-2021-0959, 
which proposes to require initial and repetitive ultrasonic testing 
(UT) inspections and thermal acoustic image inspections for cracks in 
certain 1st-stage LPC blades and removal of those blades that fail 
inspection. This proposed AD is also related to NPRM Docket Number FAA-
2021-0963, which proposes to require modifying the engine inlet to 
withstand fan blade failure event loads. The

[[Page 73714]]

special flight permit paragraphs in those proposed ADs are similar to 
the one in this proposed AD. The special flight permit paragraph 
includes a limitation requiring that the following actions have been 
done before the special flight is permitted: a flow path UT inspection 
of the 1st-stage LPC blades for cracking and the 1st-stage LPC blades 
have been found serviceable, and a functional check of the left and 
right hydraulic pump shutoff valves to ensure they close in response to 
the fire handle input within 10 days prior to flight.

Interim Action

    The FAA considers that this proposed AD would be an interim action. 
The manufacturer is currently developing other actions that will 
address the unsafe condition identified in this proposed AD. Once these 
actions are developed, approved, and available, the FAA might consider 
additional rulemaking.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 54 airplanes of U.S. registry. The FAA estimates the following 
costs to comply with this proposed AD:

                                                 Estimated Costs
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                                                                                                 Cost on U.S.
              Action                    Labor cost        Parts cost      Cost per product        operators
----------------------------------------------------------------------------------------------------------------
Installation of T/R debris         115 work-hour x $85          $4,300  $14,075............  $760,050
 shields.                           per hour = $9,775.
Inspection of fan cowl doors.....  64 work-hours x $85               0  $5,440.............  $293,760
                                    per hour = $5,440.
Functional checks of the           1 work-hour x $85                 0  $85 per inspection   $4,590 per
 hydraulic pump shutoff valves.     per hour = $85 per                   cycle.               inspection cycle.
                                    inspection cycle.
----------------------------------------------------------------------------------------------------------------

    The FAA has received no definitive data on which to base the cost 
estimates for the on-condition corrective actions specified in this 
proposed AD.

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

Regulatory Findings

    The FAA 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) Would not affect intrastate aviation in Alaska, and
    (3) Would 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.

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

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:

The Boeing Company: Docket No. FAA-2021-0962; Project Identifier AD-
2021-00997-T.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by January 27, 2022.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to The Boeing Company airplanes, certificated in 
any category, as specified in paragraphs (c)(1) and (2) of this AD.
    (1) Model 777-200 series airplanes equipped with Pratt & Whitney 
PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 
model turbofan engines.
    (2) Model 777-300 series airplanes equipped with Pratt & Whitney 
PW4090 and PW4098 model turbofan engines.

(d) Subject

    Air Transport Association (ATA) of America Code 71, Powerplant.

(e) Unsafe Condition

    This AD was prompted by reports of three incidents involving in-
flight fan blade failures on certain Pratt & Whitney engines. The 
FAA is issuing this AD to address engine fan blade failure, which 
could result in the separation of inlet and fan cowl doors and the 
thrust reverser (T/R) cowl. This could lead to engine in-flight 
shutdown, impact damage to the empennage, with significantly 
increased aerodynamic drag causing fuel exhaustion or the inability 
to maintain altitude during operations under extended-range twin-
engine operational performance standards (ETOPS) missions, and 
uncontrolled engine fire, which could result in loss of control of 
the airplane, a forced off-airport landing, and injury to 
passengers.

(f) Compliance

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

(g) Installation and Inspections

    Before further flight after the effective date of this AD, do 
the actions specified in paragraphs (g)(1) through (3) of this AD, 
in accordance with a method approved by the Manager, Seattle ACO 
Branch, FAA. Repeat the functional check specified in paragraph 
(g)(3) of this AD thereafter at intervals not to exceed 10 days.
    (1) Install debris shields on the T/R inner wall at the left and 
right sides of the lower bifurcation.
    (2) Inspect the fan cowl doors for moisture ingression. If any 
moisture ingression is found, repair before further flight.
    (3) Do a functional check of the left and right hydraulic pump 
shutoff valves to ensure they close in response to the fire

[[Page 73715]]

handle input. If any hydraulic pump shutoff valve does not close, 
before further flight perform corrective actions until it closes in 
response to the fire handle input.
    Note (1) to paragraph (g)(3): Guidance for accomplishing the 
actions required by paragraphs (g)(3) and (h)(2) of this AD can be 
found in the ``Engine-Driven Pump (EDP) Shutoff Valve Check'' 
(Subtasks 26-21-00-200-018, 26-21-00-200-019, and 26-21-00-840-022) 
of Boeing 777-200/300 Aircraft Maintenance Manual.

(h) Special Flight Permit

    Special flight permits, as described in 14 CFR 21.197 and 
21.199, are not permitted except for airplanes on which the actions 
specified in paragraphs (h)(1) and (2) of this AD have been done.
    (1) A flow path ultrasonic testing (UT) inspection of the 1st-
stage low-pressure compressor (LPC) blades for cracking has been 
done as specified in the Accomplishment Instructions, Part A--
Initial Inspection of All LPC Fan Blades Prior to their Return to 
Service, paragraph 1.A., of Pratt & Whitney Alert Service Bulletin 
PW4G-112-A72-361, dated October 15, 2021, and the 1st-stage LPC 
blades have been found serviceable.
    (2) A functional check of the left and right hydraulic pump 
shutoff valves to ensure they close in response to the fire handle 
input and all applicable corrective actions (i.e., repair) within 10 
days prior to flight.

(i) Credit for Previous Actions

    This paragraph provides credit for the actions specified in 
paragraph (h)(1) of this AD, if those actions were performed before 
the effective date of this AD using the service information 
specified in paragraph (i)(1), (2), or (3) of this AD.
    (1) Paragraph 2. of the Accomplishment Instructions of Pratt & 
Whitney Special Instruction No. 85F-21, dated May 12, 2021, for a 
flow path UT inspection.
    (2) Paragraph 1.a) of the Accomplishment Instructions of Pratt & 
Whitney Special Instruction No. 130F-21, dated July 1, 2021, for a 
flow path UT inspection.
    (3) Paragraph 2.a) of the Accomplishment Instructions of Pratt & 
Whitney Special Instruction No. 130F-21, Revision A, dated July 28, 
2021, for a flow path UT inspection.

(j) 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 responsible Flight Standards 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 (k)(1) 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 responsible Flight Standards Office.

(k) Related Information

    (1) For more information about this AD, contact James Laubaugh, 
Aerospace Engineer, Propulsion Section, FAA, Seattle ACO Branch, 
2200 South 216th St., Des Moines, WA 98198; phone and fax: 206-231-
3622; email: [email protected].
    (2) For Boeing service information identified in this AD, 
contact Boeing Commercial Airplanes, Attention: Contractual & Data 
Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 
90740-5600; telephone 562-797-1717; internet https://www.myboeingfleet.com. For Pratt & Whitney service information 
identified in this AD contact Pratt & Whitney Division, 400 Main 
Street, East Hartford, CT 06118; phone: 860-565-0140; email: 
[email protected]; website: https://connect.prattwhitney.com. 
You may view this referenced service information at FAA, 
Airworthiness Products Section, Operational Safety Branch, 2200 
South 216th St., Des Moines, WA. For information on the availability 
of this material at the FAA, call 206-231-3195.

    Issued on December 14, 2021.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2021-27838 Filed 12-22-21; 11:15 am]
BILLING CODE 4910-13-P