[4910-13-P]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-23706; Directorate Identifier 2006-NE-03-AD; Amendment 

39-18177; AD 2014-12-04]

RIN 2120-AA64

Airworthiness Directives; Honeywell International Inc. Turboprop Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

SUMMARY: We are superseding airworthiness directive (AD) 2006-15-08 for all

Honeywell International Inc. TPE331-1, -2, -2UA, -3U, -3UW, -5, -5A, -5AB, -5B, -6, 

-6A, -10, -10AV, -10GP, -10GT, -10P, -10R, -10T, -10U, -10UA, -10UF, -10UG, 

-10UGR, -10UR, -11U, -12JR, -12UA, -12UAR, and -12UHR turboprop engines with 

certain Honeywell part numbers (P/Ns) of Woodward fuel control unit (FCU) assemblies, 

installed. AD 2006-15-08 required initial and repetitive dimensional inspections of the 

fuel control drives for wear, and replacement of the FCU and fuel pump. This new AD 

requires initial and repetitive dimensional inspections of the affected fuel control drives

and insertion of certain airplane operating procedures into the applicable flight manuals.

This AD was prompted by reports of loss of the fuel control drive, leading to engine 

overspeed, overtorque, overtemperature, uncontained rotor failure, and asymmetric thrust 

in multi-engine airplanes. We are issuing this AD to prevent failure of the fuel control 

drive that could result in damage to the engine and airplane.

DATES: This AD is effective [INSERT DATE 35 DAYS AFTER DATE OF 

PUBLICATION IN THE FEDERAL REGISTER].

ADDRESSES: For service information identified in this AD, contact Honeywell
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International Inc., 111 S 34th Street, Phoenix, AZ 85034-2802; phone: 800-601-3099; 

Internet: https://myaerospace.honeywell.com/wps/portal/!ut/. You may view this service 

information at the FAA, Engine & Propeller Directorate, 12 New England Executive 

Park, Burlington, MA. For information on the availability of this material at the FAA, 

call 781-238-7125.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov by

searching for and locating Docket No. FAA-2006-23706; or in person at the Docket 

Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal 

holidays. The AD docket contains this AD, the regulatory evaluation, any comments 

received, and other information. The address for the Docket Office (phone:

800-647-5527) is Document Management Facility, 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, Aerospace Engineer, 

Los Angeles Aircraft Certification Office, FAA, Transport Airplane Directorate, 3960 

Paramount Blvd., Lakewood, CA 90712-4137; phone: 562-627-5246; fax: 562-627-5210; 

email: joseph.costa@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to 

supersede AD 2006-15-08, Amendment 39-14688 (71 FR 41121, July 20, 2006), (“AD 

2006-15-08”). AD 2006-15-08 applied to all Honeywell International Inc. TPE331-1, -2, 

-2UA, -3U, -3UW, -5, -5A, -5AB, -5B, -6, -6A, -10, -10AV, -10GP, -10GT, -10P, -10R, 

-10T, -10U, -10UA, -10UF, -10UG, -10UGR, -10UR, -11U, -12JR, -12UA, -12UAR, and 

-12UHR turboprop engines with certain Honeywell part numbers (P/Ns) of Woodward
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FCU assemblies, installed. The NPRM published in the Federal Register on March 19, 

2014 (79 FR 15261). The NPRM was prompted by reports of loss of the fuel control 

drive, leading to engine overspeed, overtorque, overtemperature, uncontained rotor 

failure, and asymmetric thrust in multi-engine airplanes. The NPRM proposed to 

continue to require initial and repetitive dimensional inspections of the affected fuel 

control drives but would no longer require the installation of a modified FCU. The

NPRM also proposed to require insertion of certain airplane operating procedures into the 

applicable flight manuals. We are issuing this AD to prevent failure of the fuel control 

drive that could result in damage to the engine and airplane.

Comments

We gave the public the opportunity to participate in developing this AD. The 

following presents the comments received on the NPRM (79 FR 15261, March 19, 2014) 

and the FAA’s response to each comment.

Disagreement with the Elimination of Requirement to Install a Modified FCU

Honeywell International Inc. (Honeywell) and an individual commenter indicated 

that the NPRM should mandate the installation of the FCU because of the benefits it 

provides. In addition, both commenters disagreed with the FAA that the modified FCU 

contributed to the rate of in-flight shutdowns (IFSDs) and that the inherent risk of 

repetitive inspections does not support the elimination of the overspeed governor (OSG) 

modification requirement of AD 2006-15-08.

We disagree. We eliminated the mandatory installation of recently certified, 

modified FCUs due to the numerous reports of unscheduled removals and the IFSDs 

caused by the recent design changes incorporated in the modified FCU. We did not 

change this AD.
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Request Change to Costs of Compliance

Honeywell indicated that the cost for repetitive inspections is not accurate. 

Honeywell estimates that, without a change in design, a limitless number of inspections

would be needed over the life of the engine.

We agree. Numerous fuel control drive inspections could be needed over the life 

of the engine. The Costs of Compliance paragraph was changed to reflect an annual cost 

of compliance which was based on the fleet costs as reflected in the NPRM.

Request to Change the Applicability

Honeywell requested that engines in Group # 4 reflect the engines associated with 

FCU assembly P/Ns being added to the Applicability paragraph for added clarity.

We agree. We changed Table 1 to paragraph (c) of this AD to clarify the Group # 

4 engine models as follows: “Group # 4 TPE331-3U, -3UW, -5, -5B, -6, -6A, and 

-10T”.

Request to Change the Applicability

Honeywell requested that clarification be provided for FCU P/Ns of Woodward 

fuel control units. The Applicability paragraph refers to P/Ns as Woodward P/Ns when 

the listed P/Ns are Honeywell P/Ns for Woodward FCUs.

We agree. We changed paragraph (c) of this AD to read, “...turboprop engines 

with Honeywell part numbers (P/Ns) for Woodward fuel control unit (FCU) assemblies 

listed in Table 1 to paragraph (c) of this AD, installed.”

Request Redundant Term be Removed from the Compliance

Honeywell requested that “spline” be removed from the fuel control drive 

inspection as stated in the Compliance paragraph. This change is consistent with the 

Compliance and the Definitions paragraphs in AD 2006-15-08.

We agree. We changed paragraphs (e)(1)(i) and (e)(2)(ii) to read: “Inspect the fuel 

control drive for wear.”
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Request to Change Related Information

Honeywell requested that the publications listed in Related Information, 

paragraph (i)(2), be referred to as airplane publications and not as obtainable from 

Honeywell International. The reason for this request is that the Airplane Flight Manual 

(AFM), the Pilot Operating Handbook (POH), and the Manufacturer’s Operating Manual 

(MOM) are airplane publications and cannot be obtained from Honeywell.

We agree that the AFM, POH, and the MOM are airplane manuals. As a result of 

reviewing this comment, we decided that mentioning all applicable owners of airplane 

manuals is unnecessary in the related information section of this AD.

Request to Change Airplane Operating Procedures

Honeywell requested that reference to the “Loss of Fuel Control Drive” be

changed to “Loss of the drive between the engine driven fuel pump and the fuel control 

governor.” This change would eliminate confusion between the loss of the accessory

drive gearing to the fuel pump with the loss of the fuel control drive.

We agree that the term “fuel control drive” is not a term used in airplane 

operating procedures. We removed the term “fuel control drive” from the Airplane 

Operating Procedures in this AD and made other changes to simplify and clarify Figure 1 

to paragraph (e) of this AD.

Request to Change Airplane Operating Procedures

One commenter requested a revision of the Operating Procedure “Warnings” in 

the NPRM to clearly address overspeed during start and immediately after start before the 

propeller has been removed from the start locks. This change would provide clarification 

and enhance safety.

We disagree. The Loss of Fuel Control Drive causing rapid, uncommanded 

acceleration during engine start is as unsafe as the Loss of Fuel Control Drive 

immediately after start when the engine is stable before the propeller is removed from the 
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start locks. However, since the observed effects for these two conditions are the same, we 

combined both instances as “Rapid, Uncommanded Acceleration During Engine Start”.

Request to Change Airplane Operating Procedures

The commenter requested changing the operating procedures for when the 

propeller is off the start locks to address the rapid uncommanded, uncontrolled increase 

in revolutions-per-minute (RPM). The commenter believes that if the fuel control drive 

fails when the propeller is off the start locks the engine’s propeller governor will control 

and stabilize the engine RPM.

We disagree with the commenter’s justification because test data has shown that 

the engine propeller governor will not control and stabilize the engine RPM if the fuel 

control drive fails when the propeller is off the start locks. A rapid, uncommanded, 

uncontrolled increase in RPM is most evident during partial or full reverse. We simplified

the operating procedure by removing the statement “ Power - Move power lever to or

toward flight idle as required to maintain engine limits” with the propeller off the start 

locks as proposed in the NPRM. We changed Figure 1 to paragraph (e) of this AD by

adding the following: “Engine shut down - Move condition lever to EMERGENCY 

STOP”.

Conclusion

We reviewed the relevant data, considered the comments received, and 

determined that air safety and the public interest require adopting this AD with the 

changes described previously and minor editorial changes. We have determined that these 

minor changes:

 Are consistent with the intent that was proposed in the NPRM for correcting 

the unsafe condition; and

 Do not add any additional burden upon the public than was already proposed 

in the NPRM.
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We also determined that these changes will not increase the economic burden on 

any operator or increase the scope of this AD.

Costs of Compliance

We estimate that this AD will affect 2,250 engines installed on airplanes of U.S. 

registry. We estimate that it will take 8 hours per engine to perform an FCU inspection.

The average labor rate is $85 per hour. Due to the more frequent inspections proposed by

this AD, we estimate 10% of affected engines will require FCU assembly stub shaft 

replacement, and fuel pump or fuel control repair. We also estimate that repairs will not

exceed $10,000 per engine. Based on these figures, we estimate the cost of this AD on 

U.S. operators to be $525,587 per year.

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.

We are 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

We have determined that this AD will not have federalism implications under 

Executive Order 13132. This AD will not have a substantial direct effect on the States, on 
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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) Is not a “significant rule” under DOT Regulatory Policies and Procedures 

(44 FR 11034, February 26, 1979),

(3) Will not affect intrastate aviation in Alaska to the extent that it justifies 

making a regulatory distinction, and

(4) 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

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. The FAA amends § 39.13 by removing airworthiness directive (AD) 2006-15-

08, Amendment 39-14688 (71 FR 41121, July 20, 2006), and adding the following new 

AD:

2015-12-04 Honeywell International Inc.: Amendment 39-18177454851; Docket 

No. FAA-2006-23706; Directorate Identifier 2006-NE-03-AD.
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(a) Effective Date

This AD is effective [INSERT DATE 35 DAYS AFTER DATE OF 

PUBLICATION IN THE FEDERAL REGISTER].

(b) Affected ADs

This AD replaces AD 2006-15-08, Amendment 39-14688 (71 FR 41121, July 20,

2006).

(c) Applicability

This AD applies to all Honeywell International Inc. TPE331-1, -2, -2UA, -3U, 

-3UW, -5, -5A, -5AB, -5B, -6, -6A, -10, -10AV, -10GP, -10GT, -10P, -10R, -10T, -10U, 

-10UA, -10UF, -10UG, -10UGR, -10UR, -11U, -12JR, -12UA, -12UAR, and -12UHR 

turboprop engines with Honeywell part numbers (P/Ns) for Woodward fuel control unit 

(FCU) assemblies listed in Table 1 to paragraph (c) of this AD, installed.

Table 1 to Paragraph (c) – Affected FCU Assembly P/Ns

Group # Engine FCU Assembly P/Ns

1 TPE331-1, -2, and -2UA P/N 869199-13, -20, -21, -22, -23, -24, -25, 

-26, -27, -28, -29, -31, -32, -33, -34, and 

-35

2* TPE331-1, -2, and -2UA P/N 869199-9, -10, -11, -12, -14, -16, -17,

and -18

3 TPE331-3U, -3UW, -5, -5A, 

-5AB, -5B, -6, -6A, -l0AV, 

-10GP, -10GT, -l0P, and -l0T

P/N 893561-7, -8, -9, -10, -11, -14, -15, 

-16, -20, -26, -27, and -29; or

P/N 897770-1, -3, -7, -9, -10, -11, -12, -14,

-15, -16, -25, -26, and -28

4* TPE331-3U, -3UW, -5, -5B, -6, 

-6A, and -10T

P/N 893561-4, -5, -12, and -13 or P/N 

897770-5, -8, and -13
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5 TPE331-10, -l0R, -10U, -10UA, 

-10UF, -10UG, -10UGR, 

-10UR, -11U, -12JR, -12UA, 

-12UAR, and -12UHR

P/N 897375-2, -3, -4, -5, -8, -9, -10, -11, 

-12, -13, -14, -15, -16, -17, -19, -21, -24, 

-25, -26, and -27; or

P/N 897780-1, -2, -3, -4, -5, -6, -7, -8, -9, 

-10, -11, -14, -15, -16, -17, -18, -19, -20, 

-21, -22, -23, -24, -25, -26, -27, -30, -32, 

-34, -36, -37, and -38; or

P/N 893561-17, -18, and -19

* New/added FCU assembly P/Ns

(d) Unsafe Condition

We are issuing this AD to prevent failure of the fuel control drive that could result 

in damage to the engine and airplane.

(e) Compliance

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

(1) Inspection of Engines with FCU Assembly P/Ns in Groups 2 and 4

For FCU assembly P/Ns in Groups 2 and 4 listed in Table 1 to paragraph (c) of 

this AD:

(i) At the next scheduled inspection of the fuel control drive, or within 500 hoursin-service (HIS) after the effective date of this AD, whichever occurs first, inspect the 

fuel control drive for wear.

(ii) Thereafter, re-inspect the fuel control drive within every 1,000 HIS since-lastinspection (SLI).

(2) Inspection of Engines with FCU Assembly P/Ns in Groups 1, 3, and 5

For FCU assembly P/Ns in Groups 1, 3, or 5 listed in Table 1 to paragraph (c) of 

this AD:

(i) If on the effective date of this AD the FCU assembly has 950 or more HIS SLI, 

inspect the fuel control drive for wear within 50 HIS from the effective date of this AD.

(ii) If on the effective date of this AD the FCU assembly has fewer than 950 HIS 

SLI, inspect the fuel control drive for wear before reaching 1,000 HIS.
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(iii) Thereafter, re-inspect the fuel control drive for wear within every 1,000 HIS 

SLI.

(3) Airplane Operating Procedures

Within 60 days after the effective date of this AD, insert the information in Figure 

1 to paragraph (e) of this AD, into the Emergency Procedures Section of the Airplane 

Flight Manual (AFM), Pilot Operating Handbook (POH), and the Manufacturer’s 

Operating Manual (MOM).

Figure 1 to Paragraph (e) – Airplane Operating Procedures

NOTE

Procedures in dotted line boxes are immediate action items to be 

performed by the pilot / flight crew.

WARNING

Do not attempt to re-start engine. Report to maintenance.

ON GROUND or IN FLIGHT:



WARNING

Never retard the power levers aft of flight idle in flight or on the ground.

WARNING

Do not attempt an engine re-start. Report to maintenance.

RAPID, UNCOMMANDED ACCELERATION DURING

ENGINE START (Propeller ON Start Locks)

 Engine Start – Abort Immediately – Move condition lever to 

EMERGENCY STOP.

RAPID, UNCOMMANDED INCREASE IN RPM, TORQUE, 

FUEL FLOW AND/OR TURBINE TEMPERATURE 

(Propeller OFF Start Locks)

 Identify Malfunctioning Engine (multi-engine airplane) –

Cross check for high torque, RPM, fuel flow, and turbine 

temperatures.

 Engine shut down - Move condition lever to EMERGENCY 

STOP.
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(f) Optional Terminating Action

Replacing the affected FCU assembly with an FAA-approved FCU assembly P/N

not listed in this AD is terminating action for the initial and repetitive inspections 

required by this AD, and for inserting the information in Figure 1 to paragraph (e) of this 

AD into the AFM, POH, and MOM.

(g) Definitions

For the purposes of this AD:

(1) The “fuel control drive” is a series of mating splines located between the fuel 

pump and fuel control governor.

(2) The fuel control drive consists of four drive splines: the fuel pump internal 

spline, the fuel control external “quill shaft” spline, and the stub shaft internal and 

external splines.

(h) Alternative Methods of Compliance (AMOCs)

The Manager, Los Angeles Aircraft Certification Office, FAA, may approve 

AMOCs for this AD. Use the procedures found in 14 CFR 39.19 to make your request.

(i) Related Information

(1) For more information about this AD, contact Joseph Costa, Aerospace 

Engineer, Los Angeles Aircraft Certification Office, FAA, Transport Airplane 

Directorate, 3960 Paramount Blvd., Lakewood, CA 90712-4137; phone: 562-627-5246; 

fax: 562-627-5210; email: joseph.costa@faa.gov.

(2) Information pertaining to operating recommendations for affected engines 

after a fuel control drive failure is contained in Honeywell International Inc., Operating 

Information Letter (OIL) OI331-12R6, dated May 26, 2009, for multi-engine airplanes; 

and in OIL OI331-18R4, dated May 26, 2009, for single-engine airplanes. Information on 

fuel control drive inspection can be found in Section 72-00-00 of the applicable TPE331

maintenance manuals. These Honeywell International Inc., OILs and the TPE331 
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maintenance manuals, which are not incorporated by reference in this AD, can be 

obtained from Honeywell International Inc., using the contact information in paragraph 

(i)(3) of this AD.

(3) For service information identified in this AD, contact Honeywell International 

Inc., 111 S. 34th Street, Phoenix, AZ 85034-2802; Internet: 

https://myaerospace.honeywell.com/wps/portal/!ut; phone: 800-601-3099.

(4) You may view this service information at the FAA, Engine & Propeller 

Directorate, 12 New England Executive Park, Burlington, MA. For information on the 

availability of this material at the FAA, call 781-238-7125.

(j) Material Incorporated by Reference

None.

Issued in Burlington, Massachusetts, on June 5, 2015.

Ann C. Mollica,

Acting Directorate Manager, Engine & Propeller Directorate,

Aircraft Certification Service.