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. 98-SW-29-AD; Amendment 39-10899; AD 98-24-13]

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. That AD also requires repairing certain cracks,

if found, and repairing and reporting those loose rivets and certain

other cracks, if found. This amendment requires the same inspections,

repairs, and reporting as the existing AD, but changes the reference to

the service bulletin and

[[Page 64176]]

prohibits the use of blind rivets for the vertical fin spar repair.

This amendment is prompted by an accident that occurred on April 15,

1997, resulting in one fatality. 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 December 4, 1998.

The incorporation by reference of Eurocopter Alert Service Bulletin

MBB-BK 117-30-106, Revision 4, dated December 19, 1997, as listed in

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

of December 4, 1998.

The incorporation by reference of Eurocopter Alert Service Bulletin

No. MBB-BK 117-30-106, Revision 3, dated May 5, 1997, as listed in the

regulations, was approved previously by the Director of the Federal

Register as of October 24, 1997 (62 FR 52655, October 9, 1997).

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

before January 19, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 98-SW-29-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 the 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. That priority letter AD required that

the inspection be performed before further flight, then repeated at

intervals not to exceed 100 hours time-in-service (TIS). That action

was prompted by an accident involving a Eurocopter Model MBB-BK117

series helicopter that 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. The crack propagated across the spar cap and spar.

A crack in the skin propagated 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.

On September 26, 1997 the FAA issued AD 97-20-16, Amendment 39-

10153 (62 FR 52655, October 9, 1997), superseding priority letter AD

97-09-16 to require the same initial and repetitive inspections of the

vertical fin spar, and additionally, requiring the repair of certain

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

other cracks. That action was prompted by the issuance of Eurocopter

Alert Service Bulletin (ASB) No. MBB-BK 117-30-106, Revision 3, dated

May 5, 1997, which contains repair procedures for the cracks that were

unavailable at the time of the release of priority letter AD 97-09-16.

The requirements of both those ADs are intended to prevent failure of

the vertical fin spar and subsequent loss of control of the helicopter.

Since the issuance of AD 97-20-16, Eurocopter has issued Eurocopter

ASB MBB-BK117 No. ASB-MBB-BK 117-30-106, Revision 4, dated December 19,

1997, which replaces all previous revisions and specifies repair

procedures for the spar cap as well as inspection requirements. It also

deletes a reference that allows the use of blind rivets for the

vertical fin spar repair.

These helicopter models are manufactured in The Federal Republic of

Germany and are 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 airworthiness

agreement. Pursuant to this bilateral airworthiness agreement, the

Luftahrt-Bundesamt (LBA), the airworthiness authority for The Federal

Republic of Germany, has kept the FAA informed of the situation

described above. The LBA superseded AD No. 97-144/2, dated June 5,

1997, with AD 1997-144/3, effective May 11, 1998. 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 A-1, A-3, A-4, B-

1, B-2, and C-1 helicopters of the same type design, this AD supersedes

AD 97-20-16, Amendment 39-10153 (62 FR 52655, October 9, 1997) to

require inspecting both surfaces of the vertical fin spar, 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 TIS 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 ASB MBB-

BK 117 No. ASB-MBB-BK 117-30-106, Revision 4, dated December 19, 1997,

or in accordance with Eurocopter ASB No. MBB-BK 117-30-106, Revision 3,

dated May 5, 1997, except use of blind rivets is not permitted.

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 for further evaluation. 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 October 24, 1997. Thereafter, the repetitive

visual inspections for cracks are required at intervals not to exceed

300 hours TIS. The actions are required to be accomplished in

accordance with the service bulletins described. The

[[Page 64177]]

short compliance time involved is required because the previously

described critical unsafe condition can adversely affect the structural

integrity of the helicopter. Therefore, inspections, reporting, and

repairs, if necessary, are required prior to further flight, and this

AD must be issued immediately.

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.

The FAA estimates that 132 helicopters will be affected by this AD,

that it will take approximately 4 work hours for each inspection and 35

hours for each repair, if necessary, per helicopter, and that the

average labor rate is $60 per work hour. Required parts will cost

approximately $302 per helicopter. Based on these figures, the total

cost impact of the AD on U.S. operators is estimated to be $348,744,

assuming one inspection and one repair per helicopter.

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. 98-SW-29-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 removing Amendment 39-10153 (62 FR

52655, October 9, 1997), and by adding a new airworthiness directive

(AD), Amendment 39-10899, to read as follows:

AD 98-24-13 Eurocopter Deutschland GmbH (ECD): Amendment 39-10899.

Docket No. 98-SW-29-AD. Supersedes AD 97-20-16, Amendment 39-10153,

Docket No. 97-SW-15-AD.

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

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.

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(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 (ASB) MBB-BK 117 No.

ASB-MBB-BK 117-30-106, Revision 4, dated December 19, 1997, or in

accordance with Eurocopter ASB No. MBB-BK 117-30-106, Revision 3,

dated May 5, 1997, except use of blind rivets is not permitted.

Thereafter, perform the inspection described in paragraph (a) of

this AD at intervals not to exceed 300 hours TIS.

(c) 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-

30402.08, 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, until the repair is

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

Fin,'' to Eurocopter ASB MBB-BK 117 No. ASB-MBB-BK 117-30-106,

Revision 4, dated December 19, 1997, or in accordance with the

Appendix, ``Repair of BK117 Vertical Fin,'' to Eurocopter ASB No.

MBB-BK 117-30-106, Revision 3, dated May 5, 1997, except use of

blind rivets is not permitted, perform the visual inspection

required by paragraph (a) of

[[Page 64179]]

this AD at intervals not to exceed 100 hours TIS.

(e) Within 600 hours TIS after October 24, 1997, accomplish the

repair to the vertical fin in accordance with the Appendix, ``Repair

of BK117 Vertical Fin,'' to Eurocopter ASB MBB-BK-117 No. ASB-MBB-BK

117-30-106, Revision 4, dated December 19, 1997, or in accordance

with the Appendix, ``Repair of BK117 Vertical Fin,'' to Eurocopter

ASB No. MBB-BK 117-30-106, Revision 3, dated May 5, 1997, except use

of blind rivets is not permitted. If blind rivets were previously

used to accomplish the vertical fin repair, they must be removed and

replaced with solid rivets to comply with the requirements of this

AD. 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.

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 repairs shall be done in accordance with

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

Service Bulletin MBB-BK 117-30-106, Revision 4, dated December 19,

1997, or in accordance with the Appendix, ``Repair of BK117 Vertical

Fin,'' to Eurocopter Alert Service Bulletin No. MBB-BK 117-30-106,

Revision 3, dated May 5, 1997, except use of blind rivets is not

permitted. The incorporation by reference of Eurocopter Alert

Service Bulletin No. MBB-BK 117-30-106, Revision 3, dated May 5,

1997, was approved previously by the Director of the Federal

Register, in accordance with 5 U.S.C. 552(a) and 1 CFR part 51, as

of October 24, 1997 (62 FR 52655, October 9, 1997). The

incorporation by reference of Eurocopter Alert Service Bulletin MBB-

BK 117-30-106, Revision 4, dated December 19, 1997, 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 the 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: Accomplishment of the requirements of Revision 3 of the

referenced service bulletin, except for using solid rivets instead

of blind rivets, or Revision 4 of the referenced service bulletin

constitutes compliance with the requirements of this AD.

(i) This amendment becomes effective on December 4, 1998.

Note 4: The subject of this AD is addressed in Luftahrt-

Bundesamt (Germany) AD 1997-144/3, effective May 11, 1998.

Issued in Fort Worth, Texas, on November 12, 1998.

Henry A. Armstrong,

Manager, Rotorcraft Directorate, Aircraft Certification Service.

[FR Doc. 98-30788 Filed 11-18-98; 8:45 am]

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