Airworthiness Directives; Hamilton Standard 14RF, 247F, 14SF, and P6/5500/F Series Propellers

SUMMARY: This amendment supersedes an existing airworthiness directive

(AD), applicable to Hamilton Standard 14RF, 247F, 14SF, and 6/5500/F

(formerly Hamilton Standard/British Aerospace 6/5500/F) series

propellers, that currently requires initial and repetitive inspections

of the propeller control unit (PCU) servo ballscrew internal spline

(BIS) teeth for wear, and replacement, if necessary, of PCU servo BIS

assemblies. This amendment increases the repetitive inspection interval

from 500 to 1,500 hours time in service (TIS) since last inspection for

propellers that have a ballscrew quill damper installed. This amendment

is prompted by the availability of improved hardware that restricts

quill motion and enhances the lubrication of the BIS and significantly

reduces BIS wear. The actions specified by this AD are intended to

prevent inability to control the propeller blade angle due to tooth

wear in the PCU servo BIS assembly.

DATES: Effective December 5, 1994.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of December 5, 1994.

ADDRESSES: The service information referenced in this AD may be

obtained from Hamilton Standard, One Hamilton Road, Windsor Locks, CT

06096-1010. This information may be examined at the Federal Aviation

Administration (FAA), New England Region, Office of the Assistant Chief

Counsel, 12 New England Executive Park, Burlington, MA 01803-5299; or

at the Office of the Federal Register, 800 North Capitol Street, NW.,

suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Frank Walsh, Aerospace Engineer,

Boston Aircraft Certification Office, FAA, Engine and Propeller

Directorate, 12 New England Executive Park, Burlington, MA 01803-5299;

telephone (617) 238-7158, fax (617) 238-7199.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal

Aviation Regulations (14 CFR part 39) by superseding AD 93-16-02,

Amendment 39-8659 (58 FR 44441, August 23, 1993), which is applicable

to Hamilton Standard 14RF, 247F, 14SF, and 6/5500/F (formerly Hamilton

Standard/British Aerospace 6/5500/F) series propellers, was published

in the Federal Register on May 27, 1994 (59 FR 27510). That action

proposed to increase the repetitive inspection interval from 500 to

1,500 hours time in service (TIS) since last inspection for propellers

that have a ballscrew quill damper installed.

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the comments received.

Seven commenters concur with the rule as proposed.

One commenter concurs with the proposal to extend the repetitive

inspection interval from 500 to 1,500 hours TIS, but also states that

paragraph (a)(5) of the NPRM requires inspection at 1,500 hours TIS if

a damper is installed, but previously ``new'' PCU's were not required

to be inspected until 1,800 hours TIS since new. The commenter further

states that this interval is not consistent since it is a decrease of

300 hours with the improved hardware, and recommends the interval to be

extended to 1,800 hours TIS for new PCU's. The FAA concurs and has

revised this final rule accordingly.

The commenter also recommends the following changes to Appendix 1

of the NPRM:

The commenter states that the date of the damper installation

should not be required since those receiving a ``new'' PCU or one from

a repair station where the damper was installed may not have access to

the actual installation date. What should be required is an answer to

the question, ``Damper installed?'' (answer either ``Yes'' or ``No''),

and if ``Yes'', and the indication of whether it was installed ``at

this inspection'' or ``previously.'' The FAA concurs and has revised

this final rule accordingly.

The commenter states that the requirement to list the aircraft

model is not required provided the PCU part number is complete with the

dash or ``A'' number. The FAA concurs and has revised this final rule

accordingly.

The commenter states that blanks are not needed for the items

``Estimated Time on PCU'' and ``Actual Time on PCU.'' What is needed is

an indication as to which one of those statements applies to the

following: ``Time Since New (hours)'' and ``Time Since Last Ballscrew

Inspection/Repair (hours).'' The FAA concurs and has revised this final

rule accordingly.

The commenter states that there is no requirement to indicate (a

reminder to complete) completion of the ``pull check'' of the PCU quill

after it is reinstalled. The FAA concurs and has added this item to

Appendix 1 of this final rule.

Two commenters indicate that the installation of the damper had

merit and should reduce the PCU's vulnerability to wear. However, the

commenters believe that the inspection interval should not be extended

to 1,500 hours TIS for the following reasons:

The first commenter states that the root cause or single reason for

the ballscrew internal spline wear has not been identified. The

Original Equipment Manufacturer (OEM) bench test of the modified

ballscrew internal spline quill installation does not demonstrate a

test that duplicates actual operation; e.g., there is retaining wire

wear due to axial preload from the damper. Also, currently there is

inadequate scientific basis for reliance on the test data as there is

insufficient field experience data.

The second commenter also states that the specific cause of wear

has not been positively identified. The proposed modification does not

correct the negative failure modes in the PCU should a wear induced

failure occur. Finally, this commenter expresses concern that the field

data used to justify the increased inspection interval is being

collected only from a small percentage of units in operation.

The FAA does not concur with these comments. The FAA has researched

these issues and reviewed the data from numerous tests and

investigations that have been conducted to determine the cause of

extreme wear when it occurs on a very small number of splines in

service. The FAA has determined that by these tests and investigations

a number of factors contribute to how or if the spline joint will wear.

These factors include:

Magnitude and direction of vibratory environment.

How well the spline joint is lubricated.

Motion of elements within the joint due to stack up of clearances.

Thickness of chrome plating on spline teeth.

The FAA has therefore determined that there is no single factor for

wear of this complex joint. However, the major contributors of the

listed factors have been found to be lubrication and axial motion.

Laboratory tests and controlled field service data has proven the

damper reduces the wear factor by well over 20 times the rate before

its installation.

The retaining wire wear is not a phenomenon associated with the

damper introduction. The retaining wires generally show some degree of

marking (mainly dents in the wire) from the flat end of the ballscrew

spline teeth bearing on the round wire. This marking occurs on

retaining wires on PCU's with and without dampers installed. After an

initial ``Seating'' of the parts, the retaining wire continues to

operate without distress.

Currently, the FAA has reported data from high time controlled

field service units in multiple model installations to have accumulated

over 2,138 hours TIS with the same damper installed. In addition, the

damper modification has been available to operators since January 1,

1994. The manufacturer has shipped over 2,800 modification kits and has

conservatively estimated that over 300,000 hours of field time has been

logged by operators with the modification installed.

Based on the investigative reports, satisfactory field inspection

data, and improved wear factors resulting from the installed damper

modification, the FAA has determined that a negative failure mode

should not occur within the new inspection interval of 1,500 hours TIS.

The FAA has therefore adopted the inspection interval stated in the

NPRM.

After careful review of the available data, including the comments

noted above, the FAA has determined that air safety and the public

interest require the adoption of the rule with the changes described

previously. The FAA has determined that these changes will neither

increase the economic burden on any operator nor increase the scope of

the AD.

There are approximately 2,506 propellers of the affected design in

the worldwide fleet. The FAA estimates that 1,150 propellers installed

on aircraft of U.S. registry will be affected by this AD, that it will

take approximately 1.5 work hours per propeller to accomplish the

required actions, and that the average labor rate is $55 per work hour.

Based on these figures, and on the average utilization rate of 2,000

hours TIS per year equating to 4 inspections, the total cost impact of

the current AD per year on U.S. operators is estimated to be $379,500.

However, based on an average utilization rate of 2,000 hours TIS per

year, this superseding AD will eliminate 2.7 inspections per year per

propeller, resulting in an approximate yearly cost savings to U.S.

operators of $256,163.

The regulations adopted herein will not have substantial direct

effects 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. Therefore, in

accordance with Executive Order 12612, it is determined that this final

rule does not have sufficient federalism implications to warrant the

preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this action (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); 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. A final evaluation has been prepared for this action

and it is contained in the Rules Docket. A copy of it may be obtained

from the Rules Docket at the location provided under the caption

ADDRESSES.

List of Subjects in 14 CFR Part 39

Air Transportation, Aircraft, Aviation safety, Incorporation by

reference, Safety.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration amends part 39 of

the Federal Aviation Regulations (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. App. 1354(a), 1421 and 1423; 49 U.S.C.

106(g); and 14 CFR 11.89.

39.13 [Amended]

2. Section 39.13 is amended by removing Amendment 39-8659 (58 FR

44441, August 23, 1993) and by adding a new airworthiness directive,

Amendment 39-9062, to read as follows:

94-22-12 Hamilton Standard: Amendment 39-9062. Docket 94-ANE-26.

Supersedes AD 93-16-02, Amendment 39-8659.

Applicability: Hamilton Standard Models 14RF-9, 14RF-19, 14RF-

21, and 14RF-23; 247F-1; 14SF-5, 14SF-7, 14SF-11, 14SFL11, 14SF-15,

14SF-17, 14SF-19, 14SF-23; and 6/5500/F propellers installed on but

not limited to Embraer EMB-120 and EMB-120RT; SAAB-SCANIA SF340B;

Aerospatiale ATR42-100, ATR42-300, ATR42-320, ATR72, ATR72-210;

DeHavilland DHC-8-100 series, DHC-8-300; Construcciones Aeronauticas

SA (CASA) CN-235 and CN-235-100; Canadair CL215T and CL415; and

British Aerospace ATP airplanes.

Compliance: Required as indicated, unless accomplished

previously.

To prevent the inability to control the propeller blade angle

due to tooth wear in the propeller control unit (PCU) servo

ballscrew internal spline (BIS) assembly, accomplish the following:

(a) Inspect the PCU servo BIS assembly for tooth wear in

accordance with the Accomplishment Instructions of the following

Hamilton Standard Alert Service Bulletins (ASB), all dated April 7,

1994, as applicable: No. 14RF-9-61-A53, Revision 5; No. 14RF-19-61-

A25, Revision 4; No. 14RF-21-61-A38, Revision 4; No. 247F-61-A3,

Revision 3; No. 14SF-61-A59, Revision 4; and No. 6/5500/F-61-A11,

Revision 4; as follows:

(1) For a PCU with unknown time in service (TIS), and unknown

TIS since the last inspection, on the effective date of this

airworthiness directive (AD), and that does not have a ballscrew

quill damper installed, inspect within 200 hours TIS after the

effective date of this AD.

(2) For a PCU with 1,800 or more hours TIS or unknown TIS on the

effective date of this AD, and either has not been inspected, or has

been inspected more than 500 hours prior to the effective date of

this AD, in accordance with the applicable Hamilton Standard ASB

listed in paragraph (a) of this AD; and that does not have a

ballscrew quill damper installed; inspect within 200 hours TIS after

the effective date of this AD.

(3) For a PCU with 1,800 or more hours TIS or unknown TIS on the

effective date of this AD, and that has been inspected within the

previous 500 hours TIS in accordance with the applicable Hamilton

Standard ASB listed in paragraph (a) of this AD, and that does not

have a ballscrew quill damper installed, inspect within 500 hours

TIS since the last inspection in accordance with the applicable

Hamilton Standard ASB listed in paragraph (a) of this AD.

(4) For a PCU with less than 1,800 hours TIS on the effective

date of this AD, and that does not have a ballscrew quill damper

installed, inspect prior to accumulating 1,800 hours TIS, or within

300 hours TIS after the effective date of this AD, whichever occurs

later.

(5) For a PCU that has a ballscrew quill damper installed in

accordance with the following applicable Hamilton Standard Service

Bulletins (SB), or previous revisions: No. 14SF-61-67, Revision 2,

dated September 27, 1994; No. 14RF-9-61-61, Revision 1, dated

September 27, 1994; No. 14RF-19-61-29, Revision 2, dated September

27, 1994; No. 14RF-21-61-48, Revision 2, dated September 27, 1994;

No. 247F-61-6, Revision 2, dated September 27, 1994; and No. 6/5500/

F-61-19, Revision 2, dated September 27, 1994; inspect within 1,500

hours TIS since installation of the ballscrew quill damper.

(6) Thereafter, inspect at intervals described as follows:

(i) For propellers that have a ballscrew quill damper installed

in accordance with the applicable Hamilton Standard SB listed in

paragraph (a)(5) of this AD, or previous revisions, inspect at

intervals not to exceed 1,500 hours TIS since the last inspection

required by this AD.

(ii) For propellers that do not have a ballscrew quill damper

installed in accordance with the applicable Hamilton Standard SB

listed in paragraph (a)(5) of this AD, inspect at intervals not to

exceed 500 hours TIS since the last inspection required by this AD.

(7) If PCU servo BIS teeth are worn beyond the limits specified

in the Accomplishment Instructions of the applicable ASB's listed in

paragraph (a) of this AD, prior to further flight, replace the PCU

with a serviceable assembly in accordance with the Accomplishment

Instructions of the applicable ASB's listed in paragraph (a) of this

AD, and thereafter reinspect in accordance with paragraphs (a)(6)

and (a)(7) of this AD.

(b) Report the results of the initial and repetitive inspections

required by paragraph (a) of this AD by utilizing Appendix 1,

``Ballscrew Inspection Data,'' within 7 days of the inspection to

the Manager, Boston Aircraft Certification Office, Engine and

Propeller Directorate, Aircraft Certification Service, FAA, 12 New

England Executive Park, Burlington, MA 01803-5299; fax (617) 238-

7199. The reporting requirements of this AD terminate on December

31, 1995. Information collection requirements contained in this

regulation have been approved by the Office of Management and Budget

(OMB) under the provision of the Paperwork Reduction Act of 1980 (44

U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-

0056.

Appendix 1--Ballscrew Inspection Data

The following information must be reported and sent as soon as

possible but no later than 7 days after inspection to: Manager,

Boston Aircraft Certification Office, Engine and Propeller

Directorate, Aircraft Certification Service, Federal Aviation

Administration, 12 New England Executive Park, Burlington, MA 01803-

5299, Fax: (617) 238-7199.

Operator/Repair Station------------------------------------------------

Date of Inspection-----------------------------------------------------

PCU Part Number--------------------------------------------------------

PCU Serial Number------------------------------------------------------

Date Damper Installed--------------------------------------------------

Damper Installed (please circle one): YES NO

If ``YES,'' please circle one: This inspection Previously

Aircraft Serial Number-------------------------------------------------

Position (please check one): Left Engine______ Right Engine______

PCU Times (please circle one): Estimated Actual

Time Since New (Hours)-------------------------------------------------

Time Since Last Ballscrew Inspection/Repair (Hours)______

Inspection (please check one): Accepted______ *Rejected______

*Please indicate in comments if unit was rejected as part of the

functional check.

No. of left side teeth with steps______

No. of right side teeth with steps______

Comments:--------------------------------------------------------------

Ballscrew Quill Pull Check Completed (please circle one): YES NO

(c) An alternative method of compliance or adjustment of the

compliance time that provides an acceptable level of safety may be

used if approved by the Manager, Boston Aircraft Certification

Office. The request should be forwarded through an appropriate FAA

Principal Maintenance Inspector, who may add comments and then send

it to the Manager, Boston Aircraft Certification Office.

Note: Information concerning the existence of approved

alternative method of compliance with this AD, if any, may be

obtained from the Boston Aircraft Certification Office.

(d) Special flight permits may be issued in accordance with

sections 21.197 and 21.199 of the Federal Aviation Regulations (14

CFR 21.197 and 21.199) to operate the aircraft to a location where

the requirements of this AD can be accomplished.

(e) The requirements of this AD shall be done in accordance with

the following Hamilton Standard service documents:

----------------------------------------------------------------------------------------------------------------

Document No. Pages Revision Date

----------------------------------------------------------------------------------------------------------------

ASB No. 14RF-9-61-A53................................. 1 5............ April 7, 1994.

2-7 4............ March 1, 1994.

8 3............ July 28, 1993.

9 5............ April 7, 1994.

10-12 4............ March 1, 1994.

13 5............ April 7, 1994.

14-20 4............ March 1, 1994.

21 5............ April 7, 1994.

Total pages: 21

----------------------------------------------------------------------------------------------------------------

SB No. 14RF-9-61-61................................... 1-2 1............ September 27, 1994.

3-10 Original..... December 9, 1993.

11 1............ September 27, 1994.

12-14 Original..... December 9, 1993.

Total pages: 14

----------------------------------------------------------------------------------------------------------------

ASB No. 14RF-19-61-A25................................ 1 4............ April 7, 1994.

2-7 3............ March 1, 1994.

8 2............ July 28, 1993.

9 4............ April 7, 1994.

10 3............ March 1, 1994.

11 4............ April 7, 1994.

12-20 3............ March 1, 1994.

21 4............ April 7, 1994.

Total pages: 21

----------------------------------------------------------------------------------------------------------------

SB No. 14RF-19-61-29.................................. 1 2............ September 27, 1994.

2 1............ May 6, 1994.

3-10 Original..... December 9, 1993.

11 2............ September 27, 1994.

12-13 Original..... December 9, 1993.

14 1............ May 6, 1994.

Total pages: 14

----------------------------------------------------------------------------------------------------------------

ASB No. 14RF-21-61-A38................................ 1 4............ April 7, 1994.

2-7 3............ March 1, 1994.

8 2............ July 28, 1993.

9-10 4............ April 4, 1994.

11-20 3............ March 1, 1994.

21 4............ April 7, 1994.

Total pages: 21

----------------------------------------------------------------------------------------------------------------

SB No. 14RF-21-61-48.................................. 1-4 2............ September 27, 1994.

5-10 Original..... December 9, 1993.

11 2............ September 27, 1994.

12-13 Original..... December 9, 1993.

14 1............ May 6, 1994.

Total pages: 14

----------------------------------------------------------------------------------------------------------------

ASB No. 247F-61-A3.................................... 1 3............ April 7, 1994.

2-7 2............ March 1, 1994.

8 1............ July 28, 1993.

9-10 3............ April 7, 1994.

11-19 2............ March 1, 1994.

20 3............ April 7, 1994.

Total pages: 20

----------------------------------------------------------------------------------------------------------------

SB No. 247F-61-6...................................... 1-4 2............ September 27, 1994.

5-10 Original..... December 9, 1993.

11 2............ September 27, 1994.

12-13 Original..... December 9, 1993.

14 1............ May 6, 1994.

Total pages: 14

----------------------------------------------------------------------------------------------------------------

ASB No. 14SF-61-A59................................... 1 4............ April 7, 1994.

2-7 3............ March 1, 1994.

8 2............ July 28, 1993.

9-10 4............ April 7, 1994.

11-20 3............ March 1, 1994.

21 4............ April 7, 1994.

Total pages: 21

----------------------------------------------------------------------------------------------------------------

SB No. 14SF-61-67..................................... 1 2............ September 27, 1994.

2 1............ May 6, 1994.

3-9 Original..... December 9, 1993.

10 1............ May 6, 1994.

11 Original..... December 9, 1993.

12 2............ September 27, 1994.

13-15 Original..... December 9, 1993.

16 1............ May 6, 1994.

Total pages: 16

----------------------------------------------------------------------------------------------------------------

ASB No. 6/5500/F-61-A11............................... 1 4............ April 7, 1994.

2-9 3............ March 1, 1994.

10-11 4............ April 7, 1994.

12 2............ July 28, 1993.

13 3............ March 1, 1994.

14 2............ July 28, 1993.

15-20 3............ March 1, 1994.

21 4............ April 7, 1994.

Total pages: 21

----------------------------------------------------------------------------------------------------------------

SB No. 6/5500/F-61-19................................. 1 2............ September 27, 1994.

2 1............ May 6, 1994.

3-10 Original..... December 6, 1993.

11 2............ September 27, 1994.

12 Original..... December 6, 1993.

13-14 1............ May 6, 1994.

Total pages: 14

----------------------------------------------------------------------------------------------------------------

This incorporation by reference was approved by the Director of the

Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part

51. Copies may be obtained from Hamilton Standard, One Hamilton

Road, Windsor Locks, CT 06096-1010. Copies may be inspected at the

FAA, New England Region, Office of the Assistant Chief Counsel, 12

New England Executive Park, Burlington, MA; or at the Office of the

Federal Register, 800 North Capitol Street, NW., suite 700,

Washington, DC.

(f) This amendment becomes effective on December 5, 1994.

Issued in Burlington, Massachusetts, on October 26, 1994.

James C. Jones,

Acting Manager, Engine and Propeller Directorate, Aircraft

Certification Service.

[FR Doc. 94-26983 Filed 11-3-94; 8:45 am]

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