[Federal Register Volume 88, Number 99 (Tuesday, May 23, 2023)]
[Proposed Rules]
[Pages 32980-32983]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-10817]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2023-1050; Project Identifier AD-2022-00602-E]
RIN 2120-AA64


Airworthiness Directives; Honeywell International Inc. Engines

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 all Honeywell International Inc. Model AS907-1-1A and AS907-2-1G 
engines. This proposed AD was prompted by reports of compressor surge, 
including a dual engine compressor surge, during takeoff climb out 
through a steep temperature inversion, causing a loss of engine thrust 
control. This proposed AD would require either the replacement of a 
certain electronic control unit (ECU) software version installed on 
AS907-1-1A engines with updated software or the replacement of certain 
ECUs installed on AS907-1-1A engines with ECUs eligible for 
installation. This proposed AD would also require the replacement of 
certain ECUs installed on AS907-2-1G engines with ECUs eligible for 
installation. 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 July 7, 
2023.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:

[[Page 32981]]

     Federal eRulemaking Portal: Go to 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.
    AD Docket: You may examine the AD docket at regulations.gov by 
searching for and locating Docket No. FAA-2023-1050; 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: Joseph Costa, Aviation Safety 
Engineer, West Certification Branch, FAA, 3960 Paramount Boulevard, 
Lakewood, CA 90712; phone: (562) 627-5246; 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-2023-1050; Project Identifier 
AD-2022-00602-E'' 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 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 
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 
Joseph Costa, Aviation Safety Engineer, West Certification Branch, FAA, 
3960 Paramount Boulevard, Lakewood, CA 90712. 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 was notified of several reports that Honeywell 
International Inc. (Honeywell) Model AS907-1-1A and AS907-2-1G engines 
experienced compressor surge, including an AS907-1-1A dual engine 
compressor surge, during takeoff climb out through a steep temperature 
inversion, which resulted in loss of engine thrust control. The FAA 
determined that the installed ECU software version logic locked the 
engine inlet total temperature (Tt2) at 60 knots on a takeoff roll and 
that reference Tt2 remained locked until the aircraft reached 400 feet 
above ground level (AGL) or the pilot moved the throttle before 
reaching 400 AGL. The locked Tt2 is mathematically adjusted by the ECU 
software for altitude and Mach number changes as the takeoff 
progresses. During the climb to 400 feet AGL with a thermal inversion, 
the actual engine Tt2 can increase above the Tt2 that is being 
calculated by the ECU, which causes the compressor guide vanes' (CGVs) 
position to be off-schedule for the actual ambient conditions. 
Significant off-scheduling of the CGVs can lead to a compressor surge 
event. The compressor surge margin is decreased when scheduling is 
based on a colder Tt2 temperature than what the engine is actually 
running. Engine deterioration impacts compressor surge margin and can 
increase the likelihood of a dual engine compressor surge as the AS907-
1-1A and AS907-2-1G engine fleets age. Dual engine power loss due to a 
temperature inversion occurring within 75 feet AGL during takeoff climb 
out may cause the loss of thrust control of an airplane. This 
condition, if not addressed, could result in reduced controllability of 
the airplane, loss of control of the airplane, reduced ability of the 
flight crew to maintain the safe flight and landing of the airplane, 
and loss of the airplane.

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.

Proposed AD Requirements in this NPRM

    This proposed AD would require either the replacement of a certain 
ECU software version installed on AS907-1-1A engines with a software 
version eligible for installation or the replacement of certain ECUs 
installed on AS907-1-1A engines with ECUs eligible for installation. 
This proposed AD would also require the replacement of certain ECUs 
installed on AS907-2-1G engines with ECUs eligible for installation. 
ECUs with P/N 2119576-3001 or P/N 2119576-3002 installed in AS907-2-1G 
engines would be eligible for reinstallation on the AS907-2-1G engines 
until exceeding the compliance time specified in Table 2 to paragraph 
(g)(2) of this AD.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 853 engines installed on airplanes of U.S. registry. The FAA 
estimates that 175 engines installed on AS907-2-1G engines will require 
replacing two ECUs.
    The FAA estimates the following costs to comply with this proposed 
AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Replace AS907-2-1G ECUs (2 per engine)  5 work-hours x $85 per          $109,044        $109,469     $19,157,075
                                         hour = $425.
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[[Page 32982]]

    For either replacement of the AS907-1-1A ECU software or 
replacement of the AS907-1-1A ECUs, depending on the option selected by 
the operator to comply with this AD, the FAA estimates the following 
costs:

----------------------------------------------------------------------------------------------------------------
                                                                                                     Cost per
                    Action                                 Labor cost               Parts cost        product
----------------------------------------------------------------------------------------------------------------
Replace AS907-1-1A ECU software (2 per engine)  5 work-hours x $85 per hour =                 $0            $425
                                                 $425.
Replace AS907-1-1A ECU (per ECU, per engine)..  2 work-hours x $85 per hour =             61,162          61,332
                                                 $170.
----------------------------------------------------------------------------------------------------------------

    The FAA has included all known costs in its cost estimate. 
According to the manufacturer, however, some of the costs of this 
proposed AD may be covered under warranty, thereby reducing the cost 
impact on affected operators.

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:

Honeywell International Inc.: Docket No. FAA-2023-1050; Project 
Identifier AD-2022-00602-E.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by July 7, 2023.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Honeywell International Inc. (Honeywell) 
Model AS907-1-1A and AS907-2-1G engines.

(d) Subject

    Joint Aircraft System Component (JASC) Code 7300, Engine Fuel 
and Control.

(e) Unsafe Condition

    This AD was prompted by reports of compressor surge, including a 
dual engine compressor surge, during takeoff climb out through a 
steep temperature inversion, which caused a loss of engine thrust 
control. The FAA is issuing this AD to prevent loss of engine thrust 
control. The unsafe condition, if not addressed, could result in 
reduced controllability of the airplane, loss of control of the 
airplane, reduced ability of the flight crew to maintain the safe 
flight and landing of the airplane, and loss of the airplane.

(f) Compliance

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

(g) Required Actions

    (1) For AS907-1-1A engines with an ECU having part number (P/N) 
2119576-1011 and software version AS907_1011 installed, before 
exceeding the applicable compliance time in Table 1 to paragraph 
(g)(1) of this AD, either replace software version AS907_1001 with a 
software version eligible for installation; or replace the ECU with 
an ECU eligible for installation. Either the software or ECU must be 
replaced for all four ECUs installed in both airplane engines at the 
same time.
    Note 1 to paragraph (g)(1): Guidance for removing and replacing 
the ECU software or removing and replacing the ECU may be found in 
Honeywell Service Bulletin (SB) AS907-76-9031, Revision 2, dated May 
15, 2022.

          Table 1 to Paragraph (g)(1)--Model AS907-1-1A Engines
------------------------------------------------------------------------
  Engine operating time since new
               (TSN)                           Compliance time
------------------------------------------------------------------------
Greater than 5,000 hours TSN......  Within 12 months or before exceeding
                                     400 hours time-in-service (TIS),
                                     whichever occurs first after the
                                     effective date of this AD.
3,000 to 5,000 hours TSN..........  Within 18 months or before exceeding
                                     600 hours TIS, whichever occurs
                                     first after the effective date of
                                     this AD.
Fewer than 3,000 hours TSN........  Within 24 months or before exceeding
                                     800 hours TIS, whichever occurs
                                     first after the effective date of
                                     this AD.
------------------------------------------------------------------------

    (2) For AS907-2-1G engines with serial numbers (S/N) P130101 
through P130240 that have not incorporated Honeywell SB AS907-72-
9063, and for AS907-2-1G engines with S/Ns P130241 through P130336, 
and S/Ns P130101 through P130240 that

[[Page 32983]]

have incorporated Honeywell SB AS907-72-9063, before exceeding the 
applicable compliance time in Table 2 to paragraph (g)(2) of this 
AD, replace any installed ECU having P/N 2119576-3001 or P/N 
2119576-3002 with an ECU eligible for installation. All four ECUs 
installed in both airplane engines must be replaced at the same 
time.
    Note 2 to paragraph (g)(2): Guidance for removing and replacing 
the ECU may be found in Honeywell SB AS907-76-9014, Revision 6, 
dated October 10, 2022.
    Note 3 to paragraph (g)(2): Guidance for converting a standard 
flow compressor to a high flow compressor for improving surge margin 
may be found in Honeywell SB AS907-72-9063, Revision 1, dated July 
31, 2019.

          Table 2 to Paragraph (g)(2)--Model AS907-2-1G Engines
------------------------------------------------------------------------
              Engine type                        Compliance time
------------------------------------------------------------------------
Standard Flow Compressor AS907-2-1G      Within 2 years or before
 engines (engine S/Ns P130101 through     exceeding 800 hours TIS,
 P130240 that have not incorporated       whichever occurs first after
 Honeywell SB AS907-72-9063).             the effective date of this AD.
High Flow Compressor                     Within 7 years or before
 AS907[dash]2[dash]1G engines (engine S/  exceeding 2,800 hours TIS,
 Ns P130241 through P130336 and engines   whichever occurs first after
 that have incorporated Honeywell SB      the effective date of this AD.
 AS907-72-9063).
------------------------------------------------------------------------

(h) Installation Prohibition

    (1) After the effective date of this AD, do not install an ECU 
having P/N 2119576-1011 and software version AS907_1001 in any 
AS907-1-1A engine.
    (2) Do not install an ECU having P/N 2119576-3001 or P/N 
2119576-3002 in any AS907-2-1G engine if the ECU has exceeded the 
compliance time specified in Table 2 to paragraph (g)(2) of this AD.

(i) Definitions

    (1) For the purpose of this AD, for the AS907-1-1A engine, a 
``software version eligible for installation'' is a software version 
that is not software version AS907_1001.
    (2) For the purpose of this AD, for the AS907-1-1A engine, an 
``ECU eligible for installation'' is an ECU that does not have P/N 
2119576-1011.
    (3) For the purpose of this AD, for the AS907-2-1G engine, an 
``ECU eligible for installation'' is an ECU that does not have P/N 
2119576-3001 or P/N 2119576-3002.

(j) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, West Certification 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 branch, send it to the 
attention of the person identified in paragraph (k)(1) of this AD 
and email 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.

(k) Related Information

    (1) For more information about this AD, contact Joseph Costa, 
Aviation Safety Engineer, West Certification Branch, FAA, 3960 
Paramount Boulevard, Lakewood, CA 90712; phone: (562) 627-5246; 
email: [email protected].
    (2) For service information identified in this AD that is not 
incorporated by reference, contact Honeywell International Inc., 111 
South 34th Street, Phoenix, AZ 85034; phone: (800) 601-3099; 
website: myaerospace.com. You may view this service information at 
the FAA, Airworthiness Products Section, Operational Safety Branch, 
1200 District Avenue, Burlington, MA 01803. For information on the 
availability of this material at the FAA, call (817) 222-5110.

(l) Material Incorporated by Reference

    None.

    Issued on May 16, 2023.
Michael Linegang,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2023-10817 Filed 5-22-23; 8:45 am]
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