[Federal Register Volume 88, Number 233 (Wednesday, December 6, 2023)]
[Rules and Regulations]
[Pages 84690-84693]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-26636]
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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;
Amendment 39-22620; AD 2023-24-04]
RIN 2120-AA64
Airworthiness Directives; Honeywell International Inc. Engines
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
Honeywell International Inc. (Honeywell) Model AS907-1-1A and AS907-2-
1G engines. This 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 AD requires 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 AD also requires the replacement of certain ECUs installed on
AS907-2-1G engines. The FAA is issuing this AD to address the unsafe
condition on these products.
DATES: This AD is effective January 10, 2024.
ADDRESSES:
AD Docket: You may examine the AD docket at regulations.gov under
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 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: Joseph Costa, Aviation Safety
Engineer, FAA, 3960 Paramount Boulevard, Lakewood, CA 90712; phone:
(562) 627-5246; 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 Honeywell Model
AS907-1-1A and AS907-2-1G engines. The NPRM published in the Federal
Register on May 23, 2023 (88 FR 32980). The NPRM was prompted by
several reports that 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 a 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)
and surge bleed valves' (SBVs) positions to be off-schedule for the
actual ambient conditions. Significant off-scheduling of the CGVs and
the SBVs 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 may result in significant loss of airplane
thrust, which could reduce the climb gradient and result in the
airplane's inability to clear obstacles. As a result, the manufacturer
updated the software.
In the NPRM, the FAA proposed to require either the replacement of
a certain ECU software version installed on AS907-1-1A engines with an
updated software version eligible for installation or the replacement
of certain ECUs installed on AS907-1-1A engines with ECUs eligible for
installation. The NPRM also proposed to require the replacement of
certain ECUs installed on AS907-2-1G engines with ECUs eligible for
installation. The FAA is issuing this AD to address the unsafe
condition on these products.
[[Page 84691]]
Discussion of Final Airworthiness Directive
Comments
The FAA received comments from three commenters. The commenters
were Bombardier Inc. (Bombardier), Duncan Aviation, and Honeywell. All
three commenters requested changes to the proposed AD. The following
presents the comments received on the NPRM and the FAA's response to
each comment.
Request To Update Software Update Language
Bombardier requested that the FAA update the NPRM so that
references to software are consistent. Bombardier noted that in the
NPRM SUMMARY section, the phrase ``updated software'' was used, while
other portions of the AD refer to the ``software version eligible for
installation.''
The FAA acknowledges the inconsistency and has provided detail
about the updated software in the Background of this final rule.
Request To Clarify Background
Bombardier requested that the FAA include language in the
Background paragraph of this AD to explain the effect of Tt2 locking on
the SBVs.
The FAA agrees. As a result, the FAA has added language to the
Background paragraph of this AD to explain the effect of Tt2 locking
and clarify the surge bleed valves that affect surge margin.
Request To Update Unsafe Condition Description
Bombardier requested that the FAA update the language in the unsafe
condition of the NPRM Background and paragraph (e) of the proposed AD
to the following: ``may result in significant loss of overall airplane
thrust which can lead to inability of the airplane to clear the AFM OEI
net flight path (risk of obstacle collision).''
The FAA partially agrees. The unsafe condition description in
Background of this final rule was clarified to include ``which could
reduce the climb gradient and result in the airplane's inability to
clear obstacles.'' However, paragraph (e) of this AD was not changed as
a result of this comment because the consequence remains consistent
with the end-level effect if the unsafe condition is not addressed.
Request To Correct the Costs of Compliance
Honeywell suggested a change to the second sentence of the Cost of
Compliance to remove an erratum.
The FAA agrees and has changed the second sentence of the Costs of
Compliance of this final rule to refer to AS907-2-1G engines installed
on airplanes of U.S. registry.
Request To Update Labor Cost
Bombardier questioned why the work-hours for removing the ECU for
the AS907-1-1A engine are less than the work-hours for removing the ECU
for the AS907-2-1G engine.
The FAA acknowledges that the estimated work-hours should be the
same for removing an ECU from both engine models. However, the FAA
estimated one ECU will need to be replaced in the AS907-1-1A fleet.
Therefore, the FAA estimated 1 work-hour to replace the ECU and 1 work-
hour to complete the power assurance run for one engine. The FAA did
not change this AD as a result of this comment.
Request To Clarify Estimated Costs Table
Honeywell noted that the structure of the Estimated Costs table is
such that the total or individual engine model fleet cost to the U.S.
registered operators is not clearly presented.
The FAA agrees and has clarified the Costs of Compliance of this
final rule. The cost per product columns reflect the estimated costs
per engine. The AS907-1-1A cost to replace ECU software was moved to
the Estimated Costs table to show a total fleet cost assuming all ECUs
receive the software upgrade. The cost to replace the AS907-1-1A ECU
remains unchanged. The FAA has no way of knowing how many AS907-1-1A
engine operators will replace the ECU instead of the software.
Request To Change the Expression of Compliance Times
Duncan Aviation and Honeywell requested that the FAA change the
expression of compliance times throughout Tables 1 and 2 of the NPRM to
be more concise. Each of the two commenters suggested slightly
different phrasing of compliance times. Each suggested removal of the
terms ``before exceeding'' and ``hours time-in-service (TIS).'' Duncan
Aviation and Honeywell requested the order of ``whichever occurs
first'' and ``after the effective date of this AD'' be reversed. Duncan
Aviation stated that ``hours TIS'' could be misinterpreted as time
since new.
The FAA agrees that the expression of compliance times should be
clear. The FAA clarifies that ``hours TIS'' is equivalent to flight
hours. The FAA changed the compliance times in Table 1 to paragraph
(g)(1) and Table 2 to paragraph (g)(2) of this AD to read as follows:
Within X months/years or Y flight hours after the effective date of
this AD, whichever occurs first.
Request To Correct ECU Software Version Number
Honeywell requested that the FAA change the ECU software version
number in paragraph (g)(1) of the proposed AD from ``AS907_1011'' to
``AS907_1001.'' Bombardier requested that the FAA change the ECU
software part version number in paragraph (g)(1) of the proposed AD
from ``AS907_1011'' to ``AS907-1001.''
The FAA agrees with changing the ECU software version number in
paragraph (g)(1) to ``AS907_1001'' because ``AS907_1001'' is the
correct nomenclature.
Request To Update Definitions
Bombardier requested that the FAA change the part/version numbers
defined as eligible for installation. Bombardier requested that the
definitions change from excluding certain part/version numbers to
requiring certain part/version numbers because older versions of
software will not address the unsafe condition.
The FAA partially agrees. While these items may be the only items
currently eligible for installation, the definitions also allow future
approved items. This mitigates the need for an alternative method of
compliance (AMOC) for future software versions or ECU P/Ns. There is no
version of software older than AS907_1001 for the AS907-1-1A engine.
The FAA did not change this AD as a result of this comment.
Conclusion
The FAA reviewed the relevant data, considered any comments
received, and determined that air safety requires adopting this AD as
proposed. Accordingly, the FAA is issuing this AD to address the unsafe
condition on these products. Except for minor editorial changes, and
any other changes described previously, this AD is adopted as proposed
in the NPRM. None of the changes will increase the economic burden on
any operator.
Costs of Compliance
The FAA estimates that this AD affects a total of 853 engines
installed on airplanes of U.S. registry. The FAA estimates that 175
AS907-2-1G engines installed on airplanes of U.S. registry will require
replacing two ECUs per engine.
The FAA estimates the following costs to comply with this AD:
[[Page 84692]]
Estimated Costs
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Cost per Cost on U.S.
Action Labor cost Parts cost product operators
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Replace AS907-2-1G ECUs (2 per engine) 5 work-hours x $85 per $109,044 $109,469 $19,157,075
hour = $425.
Replace AS907-1-1A ECU software (2 per 5 work-hours x $85 per 0 425 * 288,150
engine). hour = $425.
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* The FAA assumes that all 678 AS907-1-1A engines installed on airplanes of U.S. registry will replace the
software in two ECUs per engine. Honeywell Model AS907-1-1A operators may replace the ECU instead of replacing
the software to comply with this AD. For replacing the ECU, the FAA estimates the following costs:
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Cost per
Action Labor cost Parts cost product
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Replace AS907-1-1A ECU (per ECU, per engine).. 2 work-hours x $85 per hour = $61,162 $61,332
$170.
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The FAA has included all known costs in its cost estimate.
According to the manufacturer, however, some of the costs of this 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
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.
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:
2023-24-04 Honeywell International Inc.: Amendment 39-22620; Docket
No. FAA-2023-1050; Project Identifier AD-2022-00602-E.
(a) Effective Date
This airworthiness directive (AD) is effective January 10, 2024.
(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 electronic control unit (ECU)
having part number (P/N) 2119576-1011 and software version
AS907_1001 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
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Engine time since new (TSN) Compliance time
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Greater than 5,000 hours TSN........... Within 12 months or 400 flight
hours (FH) after the effective
date of this AD, whichever
occurs first.
3,000 to 5,000 hours TSN............... Within 18 months or 600 FH
after the effective date of
this AD, whichever occurs
first.
[[Page 84693]]
Fewer than 3,000 hours TSN............. Within 24 months or 800 FH
after the effective date of
this AD, whichever occurs
first.
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(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 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
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Engine type Compliance time
------------------------------------------------------------------------
Standard Flow Compressor AS907-2-1G Within 2 years or 800 FH after
engines (engine S/Ns P130101 through the effective date of this AD,
P130240 that have not incorporated whichever occurs first.
Honeywell SB AS907-72-9063).
High Flow Compressor AS907-2-1G engines Within 7 years or 2,800 FH
(engine S/Ns P130241 through P130336 after the effective date of
and engines that have incorporated this AD, whichever occurs
Honeywell SB AS907-72-9063). first.
------------------------------------------------------------------------
(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 West Certification Branch, send it to
the attention of the person identified in paragraph (k) 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) Additional Information
For more information about this AD, contact Joseph Costa,
Aviation Safety Engineer, FAA, 3960 Paramount Boulevard, Lakewood,
CA 90712; phone: (562) 627-5246; email: [email protected].
(l) Material Incorporated by Reference
None.
Issued on November 29, 2023.
Victor Wicklund,
Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2023-26636 Filed 12-5-23; 8:45 am]
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