[Federal Register Volume 62, Number 196 (Thursday, October 9, 1997)]
[Rules and Regulations]
[Pages 52655-52659]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-26792]


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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

[[Page 52657]]

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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