Airworthiness Directives: Mitsubishi Heavy Industries MU-2B Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-CE-09-AD; Amendment 39-8920; AD 94-11-04]

Airworthiness Directives: Mitsubishi Heavy Industries MU-2B

Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that

applies to certain Mitsubishi Heavy Industries MU-2B series airplanes.

This action requires adjusting the engine underspeed governor minimum

stop (ground idle) and the airframe condition control linkage,

modifying the tachometer indicator markings, fabricating and installing

a placard that specifies a minimum idle speed, and incorporating

Airplane Flight Manual (AFM) revisions. An accident of one of the

affected airplanes where the propeller hub assembly failed and the

propeller separated from the airplane prompted this action. Accident

investigation analysis indicates a reduction in fatigue strength of the

propeller hub because of high vibration frequencies during ground idle

speed. The actions specified by this AD are intended to prevent

propeller hub arm assembly failure because of high vibration

frequencies during ground idle speed and possible separation of the

propeller from the airplane, which could result in loss of control of

the airplane.

DATES: Effective June 10, 1994.

The incorporation by reference of certain publications listed in

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

of June 10, 1994.

Comments for inclusion in the Rules Docket must be received on or

before July 29, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Central Region, Office of the Assistant Chief

Counsel, Attention: Rules Docket 94-CE-09-AD, room 1558, 601 E. 12th

Street, Kansas City, Missouri 64106.

Information that relates to this AD may be obtained from the Beech

Aircraft Corporation, P.O. Box 85, Wichita, Kansas 67201-0085; or

Mitsubishi Heavy Industries, Ltd., 5-1 Marunouchi 2 Chome, Chiyoda-ku,

Tokyo Japan. This information may also be examined at the Federal

Aviation Administration (FAA), Central Region, Office of the Assistant

Chief Counsel, Attention: Rules Docket 94-CE-09-AD, room 1558, 601 E.

12th Street, Kansas City, Missouri 64106; or at the Office of the

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

DC.

FOR FURTHER INFORMATION CONTACT: Mr. Charles D. Riddle, Aerospace

Engineer, FAA, Wichita Aircraft Certification Office, 1801 Airport

Road, room 100, Wichita, Kansas 67209; telephone (316) 946-4144;

facsimile (316) 946-4407.

SUPPLEMENTARY INFORMATION: A recent accident of a Mitsubishi Model MU-

2B-60 airplane where the propeller hub assembly failed and the

propeller separated from the airplane prompted the FAA and the National

Transportation Safety Board (NTSB) to investigate the vibration

frequency of these airplanes during ground idle operation. Accident

investigation analysis indicates a reduction in fatigue strength of the

propeller hub because of high vibration frequencies during ground idle

speed. These high vibration frequencies, if not corrected, eventually

will result in the above-referenced propeller hub assembly failure and

separation of the propeller from the airplane.

After examining the circumstances and reviewing all available

information related to the incidents described above, the FAA has

determined that (1) certain precautions (in addition to those taken by

previous AD actions and during initial certification of the airplane)

should be taken to minimize these high vibration frequencies during

ground idle speed; and (2) AD action should be taken to prevent the

above-referenced conditions.

Since an unsafe condition has been identified that is likely to

exist or develop in other Mitsubishi MU-2B series airplanes of the same

type design, this AD requires adjusting the engine underspeed governor

minimum stop (ground idle) and the airframe condition control linkage,

modifying the tachometer indicator markings, fabricating and installing

a placard that specifies a minimum idle speed, and incorporating

Airplane Flight Manual (AFM) revisions. The ground idle modification is

required to be accomplished in accordance with the Allied Signal

Garrett Maintenance Manual (Report No. 72-00-95 for TPE331-10-501M or

Report No. 72-00-27 for TPE331-501M or -511M), chapter 72-00-00,

General-Adjustment/Test; and chapter 76-10- 01, Control Linkage

Assembly, Maintenance Practices. The airframe control linkage

modification is required to be accomplished in accordance with chapter

6, Sec. 9.2, of the applicable Mitsubishi MU-2 maintenance manual. The

revisions to the applicable Airplane Flight Manual are as follows:

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Date and revision

Model Effective pages level

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

MU-2B-26A.............. 1, 2, Revision log 2, 1- FAA approved 1-12-77

5, 5-10, 5-13, and 5- reissued 03-25-86

23. revision 4.

MU-2B-36A.............. 1, 2, Revision log 2, 1- FAA approved 01-12-77

5, 2-10, 5-10, 5-13, reissued 02-28-86

and 5-23. revision 6.

MU-2B-40............... 1, 2, Revision log 2, 1- FAA approved 3-2-78

5, 2-10, 5-10, 5-13, 5- reissued 03-25-86

14, and 5-24. revision 4.

MU-2B-60............... 1, 2, Revision log 2, 1- FAA approved 3-2-78

5, 2-9, 5-10, 5-13, 5- reissued 09-24-85

14, and 5-24. revision 5.

MU-2B-36 Modified by 1 through 31........... FAA approved 2-1-78

STC SA2413SW. reissued 12-18-92

revision 1.

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Since a situation exists that requires the immediate adoption of

this regulation, it is found that notice and opportunity for public

prior comment hereon are impracticable, and that good cause exists for

making this amendment effective in less than 30 days.

Comments Invited

Although this action is in the form of a final rule that involves

requirements affecting immediate flight safety and, thus, was not

preceded by notice and opportunity to comment, comments are invited on

this rule. Interested persons are invited to comment on this rule by

submitting such written data, views, or arguments as they may desire.

Communications should identify the Rules Docket number and be submitted

in triplicate to the address specified above. All communications

received on or before the closing date for comments will be considered,

and this rule may be amended in light of the comments received. Factual

information that supports the commenter's ideas and suggestions is

extremely helpful in evaluating the effectiveness of the AD action and

determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the rule that might

suggest a need to modify the rule. All comments submitted will be

available, both before and after the closing date for comments, in the

Rules Docket for examination by interested persons. A report that

summarizes each FAA-public contact concerned with the substance of this

AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments

submitted in response to this notice must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket No. 94-CE-09-AD.'' The postcard will be date stamped and

returned to the commenter.

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.

The FAA has determined that this regulation is an emergency

regulation that must be issued immediately to correct an unsafe

condition in aircraft, and is not a ``significant regulatory action''

under Executive Order 12866. It has been determined further that this

action involves an emergency regulation under DOT Regulatory Policies

and Procedures (44 FR 11034, February 26, 1979). If it is determined

that this emergency regulation otherwise would be significant under DOT

Regulatory Policies and Procedures, a final regulatory evaluation will

be prepared and placed in the Rules Docket (otherwise, an evaluation is

not required). A copy of it, if filed, may be obtained from the Rules

Docket.

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.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding a new airworthiness directive

to read as follows:

94-11-04 Mitsubishi Heavy Industries, Ltd.: Amendment 39-8920;

Docket No. 94-CE-09-AD.

Applicability: The following model and serial number airplanes,

certificated in any category:

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Model Serial No.

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MU-2B-26A............. All serial numbers.

MU-2B-36A............. All serial numbers.

MU-2B-40.............. All serial numbers.

MU-2B-60.............. All serial numbers.

MU-2B-36.............. All serial numbers modified by Supplemental Type

Certificate SA2413SW.

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Compliance: Required within the next 25 hours time-in-service

after the effective date of this AD, unless already accomplished.

To prevent propeller hub arm assembly failure because of high

vibration frequencies during ground idle speed and possible

separation of the propeller from the airplane, which could result in

loss of control of the airplane, accomplish the following:

(a) Adjust the underspeed governor minimum stop (ground idle) to

a range of 76.5 percent to 78.5 percent in accordance with the

Allied Signal Garrett Maintenance Manual (Report No. 72-00-95 for

TPE331-10-501M or Report No. 72-00-27 for TPE331-501M or -511M),

chapter 72-00-00, General-Adjustment /Test; and chapter 76-10-01,

Control Linkage Assembly, Maintenance Practices.

Note 1: One clockwise turn of the adjusting screw will increase

the ground idle engine speed approximately 5 percent.

(b) Modify the airframe condition control linkage by adjusting

Rod 1 and Levers 2 and 7 as specified in Figure 1 of this AD in

accordance with Chapter 6, Sec. 9.2, of the applicable Mitsubishi

MU-2 maintenance manual.

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(c) Modify the tachometer indicator marking by accomplishing the

following:

(1) Apply red lacquer (Federal Standard 595a, number 11105 or

equivalent) to the tachometer indicator glass so that the red

operating arc extends to 76.5 percent.

Note 2: The red operating arc range will now be from 50 percent

to 76.5 percent.

(2) Using white lacquer (MIL-L-7178, color number 511 or

equivalent), apply a 1/16-inch wide by 1/4-inch long slip stripe

over the tachometer glass and indicator case at the 11:30 o'clock

position as specified in Figure 2 of this AD.

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(d) Fabricate a placard with the following words utilizing

letters at least .10-inch in height: ``Minimum engine idle speed--

76.5 percent''. Install this placard on the instrument panel in

close proximity to the tachometer within the pilot's full view.

(e) Modifying the tachometer dial through an FAA-approved

instrument repair shop to extend the red operating arc to 76.5

percent is equivalent to those actions required by paragraph (c)(1),

(c)(2), and (d) of this AD, and may be accomplished in lieu of those

actions.

(f) Incorporate the following revision into the applicable

Airplane Flight Manual:

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Date and revision

Model Effective pages level

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MU-2B-26A.............. 1, 2, Revision Log 2, 1- FAA approved 1-12-77

5, 5-10, 5-13, and 5- reissued 03-25-86

23. revision 4.

MU-2B-36A.............. 1, 2, Revision Log 2, 1- FAA approved 01-12-77

5, 2-10, 5-10, 5-13, reissued 02-28-86

and 5-23. revision 6.

MU-2B-40............... 1, 2, Revision Log 2, 1- FAA approved 3-2-78

5, 2-10, 5-10, 5-13, 5- reissued 03-25-86

14, and 5-24.. revision 4.

MU-2B-60............... 1, 2, Revision Log 2, 1- FAA approved 3-2-78

5, 2-9, 5-10, 5-13, 5- reissued 09-24-85

14, and 5-24. revision 5.

MU-2B-36 modified by 1 through 31........... FAA approved 2-1-78

STC SA2413SW. reissued 12-18-92

revision 1.

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

Secs. 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR

21.197 and 21.199) to operate the airplane to a location where the

requirements of this AD can be accomplished.

(h) An alternative method of compliance other than that

referenced in paragraph (e) of this AD or adjustment of the

compliance time that provides an equivalent level of safety may be

approved by the Manager, Wichita Aircraft Certification Office

(ACO), 1801 Airport Road, room 100, Mid-Continent Airport, Wichita,

Kansas 67209. The request shall be forwarded through an appropriate

FAA Maintenance Inspector, who may add comments and then send it to

the Manager, Wichita ACO.

Note 3: Information concerning the existence of approved

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

obtained from the Wichita ACO.

(i) The incorporation required by this AD shall be done in

accordance with the following airplane flight manual revisions (as

applicable):

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

Date and revision

Model Effective pages level

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

MU-2B-26A.............. 1, 2, Revision log 2, 1- FAA approved 1-12-77

5, 5-10, 5-13, and 5- reissued 03-25-86

23. revision 4.

MU-2B-36A.............. 1, 2, revision log 2, 1- FAA approved 01-12-77

5, 2-10, 5-10, 5-13, reissued 02-28-86

and 5-23. revision 6.

MU-2B-40............... 1, 2, revision log 2, 1- FAA approved 3-2-78

5, 2-10, 5-10, 5-13, 5- reissued 03-25-86

14, and 5-24. revision 4.

MU-2B-60............... 1, 2, revision log 2, 1- FAA approved 3-2-78

5, 2-9, 5-10, 5-13, 5- reissued 09-24-85

14, and 5-24. revision 5.

MU-2B-36 modified by 1 through 31........... FAA approved 2-1-78

STC SA2413SW. reissued 12-18-92

revsion 1.

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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 Mitsubishi Heavy Industries,

Ltd., 5-1 Marunouchi 2 Chome, Chiyoda-ku, Tokyo Japan. Copies may be

inspected at the FAA, Central Region, Office of the Assistant Chief

Counsel, room 1558, 601 E. 12th Street, Kansas City, Missouri, or at

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

7th floor, suite 700, Washington, DC.

(j) This amendment (39-8920) becomes effective on June 10, 1994.

Issued in Kansas City, Missouri, on May 19, 1994.

Dwight A. Young,

Acting Manager, Small Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-12717 Filed 5-26-94; 8:45 am]

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