[Federal Register Volume 71, Number 81 (Thursday, April 27, 2006)]
[Rules and Regulations]
[Pages 24808-24812]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-3986]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-24518; Directorate Identifier 2006-SW-10-AD; 
Amendment 39-14569; AD 2006-08-12]
RIN 2120-AA64


Airworthiness Directives; MD Helicopters, Inc. Model 600N 
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) for the MD Helicopters, Inc. (MDHI) Model 600N helicopters, that 
currently requires inspecting both upper tailboom attachment fittings, 
nut plates and both angles for a crack or thread damage, and repairing 
or replacing any cracked or damaged part. That AD also requires 
replacing the upper right tailboom attachment bolt with a new 
attachment bolt, and if the upper right attachment bolt is broken, 
replacing the three remaining attachment bolts with airworthy bolts. 
Adding a washer to each bolt and modifying both access covers is also 
required. Thereafter, inspecting the upper tailboom attachments and 
repairing or replacing

[[Page 24809]]

any cracked part is required by that AD. That AD was prompted by the 
discovery of a cracked attachment bolt on a helicopter. This AD 
requires those same actions, plus installing additional inspection 
holes in the aft fuselage skin panels and inspecting the upper and 
lower tailboom attachment fittings, the upper longerons, and the angles 
and nut plates for cracks. It also requires, within a specified time, 
replacing the upper right tailboom attachment fitting, painting the 
inspection area, and replacing existing nut plates. Additionally, it 
requires inspecting the attachment bolts for any damage or wear. This 
amendment is prompted by an accident involving a Model 600N helicopter. 
The actions specified by this AD are intended to prevent failure of the 
tailboom attachment fittings, separation of the tailboom from the 
helicopter, and subsequent loss of control of the helicopter.

DATES: Effective April 27, 2006.
    The incorporation by reference of MD Helicopters Service Bulletin 
SB600N-039, dated December 9, 2003; MD Helicopters Service Bulletin 
SB600N-043, dated April 13, 2006; and MD Helicopters Technical Bulletin 
TB600N-007, Revision 1, dated April 13, 2006, as listed in the 
regulations, is approved by the Director of the Federal Register as of 
April 27, 2006.
    The incorporation by reference of MD Helicopters Service Bulletin 
SB600N-036, dated November 2, 2001, as listed in the regulations, was 
approved previously by the Director of the Federal Register as of April 
29, 2002 (67 FR 17934, April 12, 2002).
    Comments for inclusion in the Rules Docket must be received on or 
before June 26, 2006.

ADDRESSES: Use one of the following addresses to submit comments on 
this AD:
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically;
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically;
     Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590;
     Fax: (202) 493-2251; or
     Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    You may get the service information identified in this AD from MD 
Helicopters Inc., Attn: Customer Support Division, 4555 E. McDowell 
Rd., Mail Stop M615, Mesa, Arizona 85215-9734, telephone 1-800-388-
3378, fax 480-346-6813, or on the Web at http://www.mdhelicopters.com.

Examining the Docket

    You may examine the docket that contains the AD, any comments, and 
other information on the Internet at http://dms.dot.gov, or in person 
at the Docket Management System (DMS) Docket Offices between 9 a.m. and 
5 p.m., Monday through Friday, except Federal holidays. The Docket 
Office (telephone (800) 647-5227) is located on the plaza level of the 
Department of Transportation Nassif Building at the street address 
stated in the ADDRESSES section. Comments will be available in the AD 
docket shortly after the DMS receives them.

FOR FURTHER INFORMATION CONTACT: Jon Mowery, Aviation Safety Engineer, 
FAA, Los Angeles Aircraft Certification Office, Airframe Branch, 3960 
Paramount Blvd., Lakewood, California 90712, telephone (562) 627-5322, 
fax (562) 627-5210.

SUPPLEMENTARY INFORMATION: On April 12, 2002, the FAA published AD 
2001-24-51, Amendment 39-12706 (67 FR 17934), applicable to MDHI Model 
600N helicopters, that had been issued on November 28, 2001, to all 
known operators. That AD requires, within 5 hours time-in-service 
(TIS), inspecting both upper tailboom attachment fittings, nut plates, 
and both angles for a crack or thread damage, and repairing or 
replacing any cracked or damaged part before further flight. That AD 
also requires replacing the upper right tailboom attachment bolt with a 
new bolt, and if the upper right tailboom attachment bolt is broken, 
replacing the three remaining attachment bolts with airworthy 
attachment bolts before further flight. Adding a washer to each bolt 
and modifying both access covers was also required. Thereafter, 
inspecting the upper tailboom attachments at intervals not to exceed 25 
hours TIS and repairing or replacing any cracked part is required by 
that AD. That AD was prompted by the discovery of a cracked attachment 
bolt on a helicopter. That condition, if not corrected, could result in 
failure of a tailboom attachment, loss of the tailboom, and subsequent 
loss of control of the helicopter.
    Since issuing that AD, on March 21, 2006, an accident occurred in 
Alberta, Canada, involving an MDHI Model 600N helicopter, resulting in 
one fatality. That accident may have been caused by failure of the 
thread engagement between the nut plate and bolt, and/or by cracking in 
the attachment bathtub fitting. This condition, if not corrected, could 
result in failure of the tailboom attachment fittings, separation of 
the tailboom from the helicopter, and subsequent loss of control of the 
helicopter.
    On February 2, 2005, we issued a notice of proposed rulemaking 
(NPRM), applicable to MDHI Model 600N helicopters, to supersede AD 
2001-24-51. That NPRM, Docket No. 2004-SW-16-AD (70 FR 7065, February 
10, 2005), proposed to require the same actions required by AD 2001-24-
51, and also proposed to require, before further flight, installing six 
additional inspection holes in the aft fuselage skin panels. The NPRM 
also proposed to require, within 100 hours TIS, inspecting the lower 
tailboom attachment fittings, inspecting the upper longerons at 
intervals not to exceed 1,200 flight hours, and additionally proposed a 
terminating action of modifying the fuselage aft section to strengthen 
the tailboom attachments and longerons. We anticipate withdrawing that 
NPRM. We also anticipate issuing a subsequent AD to require, within 24 
months TIS, modifying the aft fuselage to strengthen the tailboom 
attachments and the longerons.
    We have reviewed the following MDHI service information:
     MD Helicopters Service Bulletin SB600N-036, dated November 
2, 2001, which describes procedures for inspecting the tailboom 
attachment fittings, repairing damaged fittings, and installing 
inspection holes in the upper right and upper left access covers;
     MD Helicopters Service Bulletin SB600N-039, dated December 
9, 2003, which describes procedures for installing additional 
inspection holes in the fuselage, and also describes procedures for 
recurring inspections of the tailboom attachment fittings and of the 
upper longerons for cracks; and
     MD Helicopters Service Bulletin SB600N-043, dated April 
13, 2006, which describes procedures for inspecting the tailboom 
attachment fittings and attachment bolts, and replacing the nut plates, 
attachment fittings, and attachment bolts, if necessary.
     MD Helicopters Technical Bulletin TB600N-007, Revision 1, 
dated April 13, 2006, which describes procedures for modifying the 
fuselage aft section to strengthen tailboom attachment fittings and 
upper longerons.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other MDHI Model 600N

[[Page 24810]]

helicopters of the same type design, this AD supersedes AD 2001-24-51 
to require, within 5 hours TIS, installing six inspection holes in the 
aft fuselage skin panels. Then, using a borescope, inspect all four 
tailboom attachment fittings and the surrounding areas, the upper 
longerons, the upper nut plates and the upper angles for cracks. Add a 
washer to each bolt between the tailboom and the NAS1587 countersunk 
washer. If a crack is found on a right-hand angle, before further 
flight, install a new clip. If a crack is found on the left-hand angle, 
before further flight, replace the angle with an airworthy angle, or 
repair the angle in accordance with FAA-approved procedures. Finally, 
replacing the upper RH tailboom attachment bolt with a new bolt, and if 
the upper right attachment bolt is broken, replacing the three 
remaining attachment bolts with airworthy attachment bolts before 
further flight is required. Within 25 hours TIS, the following actions 
are also required:
     Inspecting all attachment fittings and surrounding areas;
     Replacing the upper right tailboom attachment fitting with 
an airworthy fitting;
     Painting the inspection area;
     Inspecting the attachment bolts for wear or damage;
     Replacing worn or damaged attachment bolts; and
     Replacing all existing nut plates with airworthy nut 
plates. Thereafter, inspect the upper tailboom attachment fittings, 
angles, and nut plates at intervals not to exceed 25 hours TIS, and 
inspect the lower tailboom attachment fittings, angles and nut plates 
at intervals not to exceed 100 hours TIS. Modifying the aft fuselage to 
strengthen the tailboom attachments and the longerons constitutes a 
terminating action for the requirements of this AD. Accomplish the 
actions by following the specified portions of the service and 
technical bulletins described previously.
    The short compliance time involved is required because the 
previously described critical unsafe condition can adversely affect the 
controllability and structural integrity of the helicopter. A portion 
of the helicopters operated in this fleet have high utilization rates. 
Drilling inspection holes and inspecting the tailboom attachment 
fittings and surrounding areas for cracks are required within 5 hours 
TIS, therefore 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 this AD will affect 18 helicopters, and:
     Initial inspections will take approximately 2 work hours;
     Repetitive inspections will take approximately 24 work 
hours; and
     The initial modification will take approximately 25 work 
hours for a total of 51 work hours per helicopter to accomplish at an 
average labor rate of $80 per work hour. Required parts will cost 
approximately $2,050 for each tailboom attachment fitting (1 per 
helicopter) and $26 for 4 nut plates and 4 rivet collars per 
helicopter. Based on these figures, which assume a rate of utilization 
of 600 hours TIS per year, resulting in 24 repetitive inspections per 
year, we estimate the total cost impact of the AD on U.S. operators to 
be approximately $6,156 per helicopter, or $110,808, for the fleet, to 
perform the inspections and replacements.

Comments Invited

    This AD is a final rule that involves requirements that affect 
flight safety and was not preceded by notice and an opportunity for 
public comment; however, we invite you to submit any written data, 
views, or arguments regarding this AD. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2006-24518; 
Directorate Identifier 2006-SW-10-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the AD. We will consider 
all comments received by the closing date and may amend the AD in light 
of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this AD. Using the search function of our docket 
Web site, you can find and read the comments to any of our dockets, 
including the name of the individual who sent the comment. You may 
review the DOT's complete Privacy Act Statement in the Federal Register 
published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov.

Regulatory Findings

    We have determined that this AD will not have federalism 
implications under Executive Order 13132. This AD will not have a 
substantial direct effect 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.
    For the reasons discussed above, I certify that the regulation:
    1. Is not a ``significant regulatory action'' under Executive Order 
12866;
    2. Is not a ``significant rule'' under the 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.
    We prepared an economic evaluation of the estimated costs to comply 
with this AD. See the DMS to examine the economic evaluation.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
subtitle VII, part A, subpart III, section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
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

0
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]

0
2. Section 39.13 is amended by removing Amendment 39-12706 (71 FR 
17934, April 12, 2002), and by adding

[[Page 24811]]

a new airworthiness directive (AD), Amendment 39-14569, to read as 
follows:

2006-08-12 MD Helicopters, Inc: Amendment 39-14569. Docket No. FAA-
2006-24518; Directorate Identifier 2006-SW-10-AD. Supersedes AD 
2001-24-51, Amendment 39-12706, Docket No. 2001-SW-57-AD.

Applicability

    Model 600N helicopters, serial numbers with a prefix ``RN'' and 
003 through 058, that have not been modified in the fuselage aft 
section to strengthen the tailboom attachments and longerons in 
accordance with MD Helicopters Technical Bulletin TB600N-007, dated 
January 12, 2004, or TB600N-007, Revision 1, dated April 13, 2006, 
certificated in any category.

Compliance

    Required as indicated.
    To prevent failure of the tailboom attachment fittings, 
separation of the tailboom from the helicopter, and subsequent loss 
of control of the helicopter, accomplish the following:

    Note 1: There is a slight discrepancy between MD Helicopters, 
Inc. Service Bulletin SB600N-036, dated November 2, 2001 (SB600N-
036) and MD Helicopters Service Bulletin SB600N-039, dated December 
9, 2003 (SB600N-039) on the vertical location of the upper left 
inspection hole. Either location is acceptable for this AD.

    (a) Within 5 hours time-in-service (TIS), unless accomplished 
previously:
    (1) Remove the tailboom fairing and tailboom. Remove both upper 
tailboom attachment access covers in accordance with the 
Accomplishment Instructions, paragraph 2.B.(2) of SB600N-036.

    Note 2: MDHI CSP-HMI-2, Section 53-40-30, pertains to the 
subject of this AD.

    (2) Using a light and a 10x or higher magnifying glass:
    (i) Inspect the right and left upper tailboom attachment 
fittings, part number (P/N) 500N3422 and 500N3422-3, respectively, 
for a crack as shown in Figure 1 of the SB600N-036. If a crack is 
found, replace any cracked attachment fitting with an airworthy 
attachment fitting before further flight.
    (ii) Inspect both upper tailboom attachment nut plates for 
thread damage or a crack. Replace any damaged or cracked nut plate 
with an airworthy nut plate before further flight.
    (iii) Inspect both angles for a crack. If a crack is found on a 
right-hand angle, P/N 500N3429-6, before further flight, install a 
new clip in accordance with the Accomplishment Instructions, 
paragraph 2.B.(5)(c) of the SB600N-036. If a crack is found on the 
left-hand angle, P/N 500N3429-7, before further flight, replace the 
angle with an airworthy angle, or repair the angle in accordance 
with FAA-approved procedures.
    (3) Replace the upper right (pilot side) tailboom attachment 
bolt (bolt) with a new bolt.
    (4) If the removed upper right pilot-side bolt is broken, 
replace the remaining three bolts with airworthy bolts before 
further flight.
    (5) Add one washer, P/N AN960C516 (NAS1149C0563R) or AN960C616 
(NAS1149C0663R), as appropriate, to each tailboom bolt between the 
tailboom and the NAS1587 countersunk washer. A minimum of two 
threads must extend past the nut plate.
    (6) Modify both access covers in accordance with the 
Accomplishment Instructions, paragraph 2.B.(6), of the SB600N-036.
    (b) Within 5 hours TIS, unless accomplished previously:
    (1) Drill four additional inspection holes in the fuselage as 
shown for the left side of the fuselage in Figure 1 of SB600N-039, 
by following the Accomplishment Instruction paragraphs of SB600N-039 
as follows:
    (i) Paragraphs 2.A.(1)(a), (b), and (d) for inspection holes at 
L166 and R166.
    (ii) Paragraphs 2.A.(2)(a), (b), and (d) for inspection holes at 
L153 and R153.
    (2) Thoroughly clean the attachment fittings and surrounding 
area. If the attachment fittings and surrounding area cannot be 
satisfactorily cleaned to accomplish a borescope inspection, then 
accomplish the actions in paragraph (c) of this AD.
    (3) Using a lighted borescope, inspect all four attachment 
fittings and the surrounding area for cracking.
    (i) If a crack is found in the upper right attachment fitting, 
accomplish the actions in paragraph (c) of this AD.
    (ii) If a crack is found in any of the other three attachment 
fittings, before further flight, accomplish the actions described in 
paragraph (f) of this AD.
    (4) Visually inspect the upper longerons for cracking in 
accordance with the Accomplishment Instructions, paragraph 2.C., of 
SB600N-039. If a crack is found in the upper longeron, accomplish 
the actions in paragraph (e) of this AD.

    Note 3: The reference in Figure 1 of SB600N-039 to the 
inspection hole at L167 mistakenly states that it was ``Added by 
SB900-036.'' Inspection holes at L167 and R167 were originally 
specified by SB600N-036.

    (c) Within 25 hours TIS, unless accomplished previously:
    (1) Thoroughly clean all attachment fittings and the surrounding 
areas, inspect the area for cracking, replace the upper right 
attachment fitting and all four nut plates, and paint the area 
inside of the attachment fittings in accordance with the 
Accomplishment Instructions, paragraph 2.B., of MD Helicopters 
Service Bulletin SB600N-043, dated April 13, 2006 (SB600N-043). If a 
crack is found in any of the other three attachment fittings, before 
further flight, accomplish the actions described in paragraph (f) of 
this AD.
    (2) Using a 10x magnifying glass, inspect the attachment bolts' 
threads and shanks for wear or damage in accordance with paragraph 
2.B., of SB600N-043. If wear or damage is present, replace the 
attachment bolts with airworthy bolts.
    (d) Thereafter, at the specified intervals, remove the plug 
buttons from the inspection holes, and using a bright light, inspect 
the upper and lower left and upper and lower right attachment 
fittings, angles, and nut plates for a crack by following the 
Accomplishment Instruction paragraphs of SB600N-039, as follows, 
except you are not required to contact MDHI to meet the requirements 
of this AD.
    (1) At intervals not to exceed 25 hours TIS, through inspection 
holes at L167 and R167, inspect the upper left and upper right 
attachment fittings, angles, and nut plates by following the 
Accomplishment Instructions, paragraphs 2.B.(2) through 2.B.(4), of 
SB600N-039.
    (2) At intervals not to exceed 100 hours TIS, through inspection 
holes at L166 and R166, inspect the lower left and lower right 
attachment fittings, angles, and nut plates by following the 
Accomplishment Instructions, paragraphs 2.B.(2) through 2.B.(4), of 
SB600N-039.
    (e) If a crack is found in the upper right attachment fitting, 
or in any angle, nut plate, longeron, or if thread wear or damage is 
found on any nut plate or bolt, before further flight, replace the 
cracked or worn or damaged part with an appropriate airworthy part, 
or accomplish the actions in paragraph (f) of this AD. If cracking 
is found in any of the other three attachment fittings, before 
further flight, accomplish the actions described in paragraph (f) of 
this AD.
    (f) If required by paragraph (c)(1) of this AD, or if you choose 
to make this modification to comply with paragraph (e) of this AD, 
modify the aft fuselage to strengthen the tailboom attachments and 
the longerons by following the Accomplishment Instructions of MD 
Helicopters Technical Bulletin TB600N-007, Revision 1, dated April 
13, 2006. Modifying the aft fuselage in accordance with this 
paragraph constitutes a terminating action for the requirements of 
this AD.
    (g) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Contact the Manager, Los Angeles Aircraft Certification Office, 
Airframe Branch, FAA, ATTN: Jon Mowery, Aviation Safety Engineer, 
3960 Paramount Blvd., Lakewood, California 90712, telephone (562) 
627-5322, fax (562) 627-5210, for information about previously 
approved alternative methods of compliance.
    (h) Special flight permits may be issued in accordance with 14 
CFR 21.197 and 21.199 to operate the helicopter to the nearest 
maintenance facility capable of performing the inspections and 
modification.
    (i) The inspections shall be done in accordance with MD 
Helicopters Service Bulletin SB600N-036, dated November 2, 2001. The 
incorporation by reference of that document 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 April 29, 2002 (67 FR 17934, April 
12, 2002). The inspections, replacements and modifications shall be 
done in accordance with MD Helicopters Service Bulletin SB600N-039, 
dated December 9, 2003; MD Helicopters Service Bulletin SB600N-043, 
dated April 13, 2006; and MD Helicopters Technical Bulletin

[[Page 24812]]

TB600N-007, Revision 1, dated April 13, 2006. The incorporation by 
reference of these documents 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 MD Helicopters Inc., Attn: Customer 
Support Division, 4555 E. McDowell Rd., Mail Stop M615, Mesa, 
Arizona 85215-9734, telephone 1-800-388-3378, fax 480-346-6813, or 
on the web at www.mdhelicopters.com. Copies may be inspected at the 
National Archives and Records Administration (NARA). For information 
on the availability of this material at NARA, call 202-741-6030, or 
go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.
    (j) This amendment becomes effective on April 27, 2006.

    Issued in Fort Worth, Texas, on April 20, 2006.
Mark R. Schilling,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 06-3986 Filed 4-26-06; 8:45 am]
BILLING CODE 4910-13-P