Airworthiness Directives; Eurocopter Deutschland GmbH (ECD) (Eurocopter) Model MBB-BK117 A-1, A-3, A-4, B-1, B-2, and C-1 Helicopters

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-SW-15-AD; Amendment 39-10153; AD 97-20-16]

RIN 2120-AA64

Airworthiness Directives; Eurocopter Deutschland GmbH (ECD)

(Eurocopter) Model MBB-BK117 A-1, A-3, A-4, B-1, B-2, and C-1

Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment supersedes an existing airworthiness directive

(AD), applicable to Eurocopter Model MBB-BK117 A-1, A-3, A-4, B-1, B-2,

and C-1 helicopters, that currently requires initial and repetitive

inspections of both surfaces of the tail boom vertical fin (vertical

fin) spar, the skin, and the left-hand and right-hand frame sheets for

cracks or loose rivets. This amendment requires the same initial and

repetitive inspections of the vertical fin spar that are required by

the existing AD, and also requires repairing certain cracks, if found,

and repairing and reporting loose rivets and certain other cracks, if

found. This amendment is prompted by an accident which occurred on

April 15, 1997, resulting in one fatality. A subsequent investigation

revealed that the vertical fin had failed as a result of a fatigue

crack that initiated on the left side of the vertical fin spar cap. The

actions specified by this AD are intended to prevent failure of the

vertical fin and subsequent loss of control of the helicopter.

DATES: Effective October 24, 1997. The incorporation by reference of

certain publications listed in the regulations is approved by the

Director of the Federal Register as of October 24, 1997.

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

before December 8, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Office of Regional Counsel, Southwest Region,

Attention: Rules Docket No. 97-SW-15-AD, 2601 Meacham Blvd., Room 663,

Fort Worth, Texas 76137.

The service information referenced in this AD may be obtained from

American Eurocopter Corporation, 2701 Forum Drive, Grand Prairie, Texas

75053-4005, telephone (972) 641-3460, fax (972) 641-3527. This

information may be examined at the FAA, Office of Regional Counsel,

Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas

76137; or at the Office of the Federal Register, 800 North Capitol

Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Mr. Richard Monschke, Aerospace

Engineer, Rotorcraft Standards Staff, 2601 Meacham Blvd., Fort Worth,

Texas 76137, telephone (817) 222-5116, fax (817) 222-5961.

SUPPLEMENTARY INFORMATION: On April 25, 1997, the FAA issued priority

letter AD 97-09-16, to require inspecting both surfaces of the vertical

fin spar, part number (P/N) 105-304061.03, P/N 1120-30406.03, or P/N

117-30423-03, paying particular attention to the area extending from

the top edge of the second lightening hole from the top of the vertical

fin spar to the bottom edge of the fourth lightening hole, the outer

skin (skin), and the left-hand and right-hand frame plates for cracks,

loose rivets, or other anomalies. This inspection must be performed

before further flight, then repeated at intervals not to exceed 100

hours time-in-service. That action was prompted by an accident

involving a Eurocopter Model MBB-BK117 series helicopter, which

occurred on April 15, 1997, resulting in one fatality. A subsequent

investigation revealed that the vertical fin had failed as a result of

a fatigue crack that initiated on the left side of the vertical fin

spar cap. The crack propagated across the spar cap and spar web until

only the skin was carrying the flight load. The skin then started

cracking, with the crack propagating horizontally toward the vertical

fin leading edge until catastrophic overstress occurred. Inspections of

other helicopters of the same type design revealed cracks in the

vertical fin spars of three additional helicopters. That condition, if

not corrected, could result in failure of the vertical fin and

subsequent loss of control of the helicopter.

Since the issuance of that AD, the manufacturer has developed

repair procedures for the cracks, which were unavailable at the time of

the release of the priority letter AD, and has issued Eurocopter Alert

Service Bulletin MBB-BK117 No. ASB-MBB-BK117-30-106, Revision 3, dated

May 5, 1997, which specifies repair procedures for the spar cap, as

well as subsequent inspection requirements.

This helicopter model is manufactured in The Federal Republic of

Germany and is type certificated for operation in the United States

under the provisions of section 21.29 of the Federal Aviation

Regulations (14 CFR 21.29) and the applicable bilateral

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airworthiness agreement. Pursuant to this bilateral airworthiness

agreement, the Luftahrt-Bundesamt (LBA) has kept the FAA informed of

the situation described above. The FAA has examined the findings of the

LBA, reviewed all available information, and determined that AD action

is necessary for products of this type design that are certificated for

operation in the United States.

Since an unsafe condition has been identified that is likely to

exist or develop on other Eurocopter Model MBB-BK117 series helicopters

of the same type design, this AD supersedes AD 97-09-16 to require

inspecting both surfaces of the vertical fin spar, part number (P/N)

105-304061.03, P/N 1120-30406.03, or P/N 117-30423-03, paying

particular attention to the area extending from the top edge of the

third lightening hole from the top of the vertical fin spar to halfway

between the fourth and fifth lightening hole (see Figure 1 for

description of area to be inspected), the skin, and the left-hand and

right-hand frame sheets for cracks or loose rivets. This inspection

must be repeated at intervals not to exceed 100 hours time-in-service

until the repair is accomplished. If a crack is found in the area of

the fourth lightening hole of the vertical fin spar, including a crack

in the cap or ``c'' channel area of the spar, or in the left-hand frame

sheet, P/N 105-304161 or P/N 1120-30416, or in the right-hand frame

sheet, P/N 105-304211 or P/N 1120-30421, before further flight, the

crack must be repaired in accordance with the repair instructions that

are an Appendix titled ``Repair of BK117 Vertical Fin'' to Eurocopter

Alert Service Bulletin MBB-BK117 No. ASB-MBB-BK117-30-106, Revision 3,

dated May 5, 1997. Thereafter, this AD requires that a visual

inspection for cracks be performed at intervals not to exceed 300 hours

TIS. If a crack or loose rivet is found in the area other than that

described in paragraph (a) of this AD, including any crack that is

found to extend into the skin, P/N 105-304011.18 or P/N 1120-30402.0,

contact the Rotorcraft Standards Staff before further flight. Further

evaluation is required before further flight. If no crack is found, the

repetitive visual inspection for cracks is required at intervals not to

exceed 100 hours TIS until the repair specified in the repair

instruction is accomplished. The repair must be accomplished within 600

hours TIS after the accomplishment of the initial inspection.

Thereafter, the repetitive visual inspections for cracks at intervals

not to exceed 300 hours TIS are required. The actions are required to

be accomplished in accordance with the service bulletin described

previously.

Since a situation exists that requires the immediate adoption of

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

public 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 flight safety and, thus, was not preceded by

notice and an opportunity for public 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 under the caption ADDRESSES. 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 rule must submit a self-addressed,

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

to Docket No. 97-SW-15-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 that it 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.

A copy of it, if filed, 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. 106(g), 40113, 44701.

Sec. 39.13 [Amended]

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

(AD), Amendment 39-10153, to read as follows:

97-20-16 Eurocopter Deutschland GmbH (ECD): Amendment 39-10153.

Docket No. 97-SW-15-AD. Supersedes priority letter AD 97-09-16.

Applicability: Model MBB-BK117 A-1, A-3, A-4, B-1, B-2, and C-1

helicopters, certificated in any category.

Note 1: This AD applies to each helicopter identified in the

preceding applicability provision, regardless of whether it has been

modified, altered, or repaired in the area subject to the

requirements of this AD. For helicopters that have been modified,

altered, or repaired so that the performance of the requirements of

this AD is affected, the owner/operator must use the authority

provided in paragraph (f) to request approval from the FAA. This

approval may address either no action, if the current configuration

eliminates the unsafe condition, or different actions necessary to

address the unsafe condition described in this AD. Such a request

should include an assessment of the effect of the changed

configuration on the unsafe condition addressed by this AD. In no

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case does the presence of any modification, alteration, or repair

remove any helicopter from the applicability of this AD.

Compliance: Required as indicated, unless accomplished

previously.

To prevent failure of the tail boom vertical fin (vertical fin)

and subsequent loss of control of the helicopter, accomplish the

following:

(a) Before further flight, remove the tail rotor drive shaft

between the intermediate and tail rotor gearboxes and the yaw servo

(if installed). Thoroughly clean the vertical fin spar and adjacent

areas and visually inspect the following for cracks or loose rivets:

(1) Both surfaces of the vertical fin spar, part number (P/N)

105-304061.03, P/N 1120-30406.03, or P/N 117-30423-03, paying

particular attention to the area extending from the top edge of the

third lightening hole from the top of the vertical fin spar to

halfway between the fourth and fifth lightening hole (see Figure 1).

(2) The skin and left-hand and right-hand frame sheets.

(b) If a crack or loose rivet is found in the area described in

paragraph (a) of this AD (see Figure 1), before further flight,

repair in accordance with the Appendix, ``Repair of BK117 Vertical

Fin'', to Eurocopter Alert Service Bulletin MBB-BK117 No. ASB-MBB-

BK117-30-106, Revision 3, dated May 5, 1997. Thereafter, perform the

inspection described in paragraph (a) of this AD at intervals not to

exceed 300 hours TIS.

(c) If a crack or lose rivet is found in the area other than

that described in paragraph (a) of this AD, including any crack that

is found to extend into the skin, P/N 105-304011.18 or P/N 1120-

30402.08, before further flight, contact the Rotorcraft Standards

Staff. Reporting requirements have been approved by the Office of

Management and Budget and assigned OMB control number 2120-0056.

(d) If no crack or loose rivet is found as a result of the

inspection required by paragraph (a) of this AD, thereafter, until

the repair is made in accordance with the Appendix, ``Repair of

BK117 Vertical Fin'', to

Eurocopter Alert Service Bulletin MBB-BK117 No. ASB-MBB-BK117-30-

106, Revision 3, dated May 5, 1997, conduct the visual inspection

required by paragraph (a) of this AD at intervals not to exceed 100

hours TIS.

(e) Within 600 hours TIS after the effective date of this AD,

accomplish the repair to the vertical fin in accordance with the

Appendix, ``Repair of BK117 Vertical Fin'', to Eurocopter Alert

Service Bulletin MBB-BK117 No. ASB-MBB-BK117-30-106, Revision 3,

dated May 5, 1997. Thereafter, perform the visual inspection

required by paragraph (a) of this AD at intervals not to exceed 300

hours TIS.

(f) 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, FAA, Rotorcraft Directorate,

Rotorcraft Standards Staff. Operators shall submit their requests

through an FAA Principal Maintenance Inspector, who may concur or

comment and then send it to the Manager, Rotorcraft Standards Staff.

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Note 2: Information concerning the existence of approved

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

obtained from the Rotorcraft Standards Staff.

(g) Special flight permits will not be issued.

(h) The inspections and repair shall be done in accordance with

Eurocopter Deutschland GmbH (ECD) Alert Service Bulletin ASB-MBB-

BK117-30-106, Revision 3, dated May 5, 1997, including Appendix.

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 American Eurocopter Corporation,

2701 Forum Drive, Grand Prairie, Texas 75053-4005, telephone (972)

641-3460, fax (972) 641-3527. Copies may be inspected at the FAA,

Office of Regional Counsel, Southwest Region, 2601 Meacham Blvd.,

Room 663, Fort Worth, Texas; or at the Office of the Federal

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

Note 3: The subject of this AD is addressed in Luftfahrt-

Bundesamt (Germany) AD 97-144/2, dated June 5, 1997.

(i) This amendment becomes effective on October 24, 1997.

Issued in Fort Worth, Texas, on September 26, 1997.

Eric Bries,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.

[FR Doc. 97-26792 Filed 10-8-97; 8:45 am]

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