Document ID: FAA-2008-0835-0001
Agency: faa
Document Type: Rule
Title: Airworthiness Directives; MD Helicopters, Inc. Model 600N Helicopters
Posted Date: 2008-10-10T04:00Z

[Federal Register: October 10, 2008 (Volume 73, Number 198)]
[Rules and Regulations]               
[Page 60102-60105]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr10oc08-3]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0835; Directorate Identifier 2008-SW-34-AD; 
Amendment 39-15684; AD 2008-20-05]
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 MD Helicopters, Inc. (MDHI) Model 600N helicopters. The AD 
currently requires modifying the fuselage aft section within the next 
24 months to

[[Page 60103]]

strengthen the tailboom attachment fittings and upper longerons. This 
amendment retains the current required modification and adds the 
following requirements: Repetitively inspecting the tailboom attachment 
fittings; installing inspection holes and attachment bolt washers; 
modifying both access covers; and replacing broken attachment bolts. 
These additional requirements were inadvertently omitted from the 
current AD. This amendment is prompted by the need to correct our 
mistake and continue the repetitive inspections of the tailboom 
attachment fittings until the fuselage aft section is modified. This 
series of ADs is prompted by an accident due to failure of the tailboom 
attach points resulting in loss of control of the 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 October 27, 2008.
    The incorporation by reference of certain publications was approved 
by the Director of the Federal Register as of April 29, 2002 (67 FR 
17934, April 12, 2002); April 27, 2006 (71 FR 24808, April 27, 2006); 
and April 16, 2008 (73 FR 13096, March 12, 2008).
    Comments for inclusion in the Rules Docket must be received on or 
before December 9, 2008.

ADDRESSES: Use one of the following addresses to submit comments on 
this AD:
     Federal eRulemaking Portal: Go to http://
www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590, 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 Internet 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://
www.regulations.gov, or in person at the Docket Operations office 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The Docket Operations office (telephone (800) 647-5527) is 
located in Room W12-140 on the ground floor of the West Building at the 
street address stated in the ADDRESSES section. Comments will be 
available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Eric Schrieber, Aviation Safety 
Engineer, FAA, Los Angeles Aircraft Certification Office, Airframe 
Branch, 3960 Paramount Blvd., Lakewood, California 90712, telephone 
562-627-5348, fax (562) 627-5210.

SUPPLEMENTARY INFORMATION: On February 27, 2008, we issued AD 2008-05-
17, Amendment 39-15411 (73 FR 13096, March 12, 2008), to supersede AD 
2006-08-12, Amendment 39-14569 (71 FR 24808, April 27, 2006), which 
superseded AD 2001-24-51, Amendment 39-12706 (67 FR 17934, April 12, 
2002), for the MDHI Model 600N helicopters. AD 2008-05-17 required 
modifying the fuselage aft section within the next 24 months to 
strengthen the tailboom attachment fittings and upper longerons. AD 
2001-24-51 was prompted by the discovery of a cracked bolt. AD 2006-08-
12 was prompted by an accident due to failure of the tail boom attach 
points resulting in loss of control of the helicopter. That 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.
    Since issuing AD 2008-05-17, we discovered that we inadvertently 
omitted the requirements from AD 2006-08-12 to repetitively inspect the 
tailboom attachment fittings; install inspection holes and attachment 
bolt washers; modify both access covers; and replace broken attachment 
bolts. Since the compliance time in AD 2008-05-17 for modifying the 
fuselage aft section is 24 months, this results in a 24-month period of 
time for which the helicopters would not be subject to the actions 
contained in AD 2006-08-12, which was not our intention. The accident 
that prompted these ADs may have resulted from failure of the thread 
engagement between the nut plate and bolt or by cracking in the 
attachment bathtub ring. Therefore, the tailboom attachment fittings 
and upper longerons must be inspected at 25- and 100-hour time-in-
service (TIS) intervals to detect any unairworthy parts and prevent 
failure of the tailboom attachment fittings, separation of the tailboom 
from the helicopter, and subsequent loss of control of the helicopter.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other MDHI Model 600N helicopters of the same type 
design, this AD supersedes AD 2008-05-17 to reinstate certain actions 
related to the tailboom attachment fittings inadvertently omitted from 
the current AD and to continue to require the modification of the 
fuselage aft section within 24 months. The inspections and modification 
must be accomplished by following the specified portions of the service 
bulletins.
    The short compliance time involved is required because the 
previously described critical unsafe condition can adversely affect the 
structural integrity and the controllability of the helicopter. The 
inspections are required at 25 and 100-hours time-in-service (TIS). We 
consider that the 100-hour TIS inspection is a relatively short 
interval because some of the affected helicopters may reach those hours 
within 2 months. Therefore, this AD must be issued immediately to 
reinstate the previous requirements related to the tailboom attachment 
fittings.
    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.
    We estimate that this AD will affect 18 helicopters and will take 
about 322 work hours to modify each helicopter and will require about 1 
work hour to do a repetitive inspection with 24 inspections per 
helicopter per year at an average labor rate of $80 per work hour. 
Required parts will cost about $14,960 per helicopter. Based on these 
figures and assuming 24 repetitive inspections per helicopter per year 
for 2 years until the modification is required, we estimate the total 
cost impact of the AD on U.S. operators to be $802,080.

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-2008-0834; Directorate 
Identifier 2008-SW-34-AD'' at the beginning of your comments. We 
specifically invite comments on the overall regulatory, economic, 
environmental, and energy aspects of

[[Page 60104]]

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://
www.regulations.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).

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 AD docket 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 39-15411 (73 FR 
13096, March 12, 2008), and by adding a new airworthiness directive 
(AD), Amendment 39-15684, to read as follows:

2008-20-08 MD Helicopters, Inc.: Amendment 39-15684. Docket No. FAA-
2008-0834; Directorate Identifier 2008-SW-34-AD. Supersedes AD 2008-
05-17, Amendment 39-15411, Docket No. FAA-2007-29342, Directorate 
Identifier 2007-SW-08-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 per MD Helicopters (MDHI) Technical Bulletin (TB) TB600N-
007, dated January 12, 2004; TB600N-007, Revision 1, dated April 13, 
2006; or TB600N-007, Revision 2, dated October 5, 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, do 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 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 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 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

[[Page 60105]]

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 make 
this modification to comply with paragraph (e) of this AD, modify 
the fuselage aft section to strengthen the tailboom attachments and 
the upper longerons by following paragraph 2, Accomplishment 
Instructions, of MDHI TB600N-007, dated January 12, 2004; TB600N-
007, Revision 1, dated April 13, 2006; or TB600N-007, Revision 2, 
dated October 5, 2006; except you are not required to contact the 
manufacturer. This modification to the fuselage aft section is 
terminating action for the requirements of this AD.
    (g) Within 24 months, modify the fuselage aft section to 
strengthen the tailboom attachments and upper longerons by following 
paragraph 2, Accomplishment Instructions, of MDHI TB600N-007, 
Revision 2, dated October 5, 2006, except you are not required to 
contact the manufacturer. This modification to the fuselage aft 
section is terminating action for the requirements of this AD.
    (h) 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: Eric Schrieber, Aviation Safety 
Engineer, 3960 Paramount Blvd., Lakewood, California 90712, 
telephone (562) 627-5348, fax (562) 627-5210, for information about 
previously approved alternative methods of compliance.
    (i) Inspect, replace, and modify the fuselage aft section 
according to the specified portions of the following MD Helicopters 
service information, as applicable.
    (1) Service Bulletin SB600N-036, dated November 2, 2001; 
incorporated by reference as of April 29, 2002 (67 FR 17934, April 
12, 2002).
    (2) Service Bulletin SB600N-039, dated December 9, 2003; Service 
SB600N-043, dated April 13, 2006; and Technical Bulletin TB600N-007, 
Revision 1, dated April 13, 2006; incorporated by reference as of 
April 27, 2006 (71 FR 24808, April 27, 2006).
    (3) Technical Bulletin TB600N-007, Revision 2, dated October 5, 
2006; incorporated by reference as of April 16, 2008 (73 FR 13096, 
March 12, 2008).
    (4) The incorporation by reference of these documents was 
approved previously by the Director of the Federal Register in 
accordance with 5 U.S.C. 552(a) and 1 CFR part 51.
    (5) Copies of this service information 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 Internet at http://
www.mdhelicopters.com.
    (6) 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 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 October 27, 2008.

    Issued in Fort Worth, Texas, on September 25, 2008.
Mark R. Schilling,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. E8-23540 Filed 10-9-08; 8:45 am]

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