[Federal Register Volume 72, Number 4 (Monday, January 8, 2007)]
[Proposed Rules]
[Pages 669-672]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-43]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-26771; Directorate Identifier 2005-SW-07-AD]
RIN 2120-AA64


Airworthiness Directives; Enstrom Helicopter Corporation Model F-
28A, F-28C, F-28F, TH-28, 280, 280C, 280F, 280FX, 480, and 480B 
Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes adopting a new airworthiness directive 
(AD) for Enstrom Helicopter Corporation (Enstrom) Model F-28A, F-28C, 
F-28F, TH-28, 280, 280C, 280F, 280FX, 480, and 480B helicopters. The AD 
would require determining the installation dates for each main rotor 
push-pull control rod (push-pull rod), inspecting the push-pull rods 
for corrosion, replacing any push-pull rod which has corrosion that is 
severe enough to cause pitting, or has visible moisture inside the rod, 
and repairing each push-pull rod that has corrosion but no pitting. 
This proposal is prompted by one reported incident in which the 
helicopter pilot encountered severe in flight vibration due to the 
failure of a push-pull rod, requiring an emergency landing. The actions 
specified by the proposed AD are intended to detect corrosion and 
prevent failure of a push-pull rod, and subsequent loss of control of 
the helicopter.

DATES: Comments must be received on or before March 9, 2007.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD:
    <bullet> DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically;
    <bullet> Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically;
    <bullet> Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590;
    <bullet> Fax: 202-493-2251; or
    <bullet> 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 proposed AD 
from The Enstrom Helicopter Corporation, Twin County Airport, P.O. Box 
490, Menominee, Michigan 49858.
    You may examine the comments to this proposed AD in the AD docket 
on the Internet at http://dms.dot.gov.

FOR FURTHER INFORMATION CONTACT: Shawn Malekpour, Aviation Safety 
Engineer, FAA, Chicago Aircraft Certification Office, 2300 East Devon 
Ave., Des Plaines, Illinois 60018, telephone (847) 294-7837, fax (847) 
294-7834.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite you to submit any written data, views, or arguments 
regarding this proposed AD. Send your comments to the address listed 
under the caption ADDRESSES. Include the docket number ``FAA-2006-
26771, Directorate Identifier 2005-SW-07-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the proposed AD. We will 
consider all comments received by the closing date and may amend the 
proposed 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 proposed rulemaking. 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 or 
signed 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.

Examining the Docket

    You may examine the docket that contains the proposed AD, any 
comments, and other information in person at the Docket Management 
System (DMS) Docket Office between 9 a.m. and 5 p.m., Monday through 
Friday, except Federal holidays. The Docket Office (telephone 1-800-
647-5227) is located at the plaza level of the Department of 
Transportation NASSIF Building in Room PL-401 at 400 Seventh Street, 
SW., Washington, DC. Comments will be available in the AD docket 
shortly after the DMS receives them.

Discussion

    This document proposes adopting a new AD for Enstrom Model F-28A, 
F-28C, F-28F, TH-28, 280, 280C, 280F, 280FX, 480, and 480B helicopters. 
The proposed AD would require reviewing the helicopter maintenance 
records and determining the installation dates for the push-pull rods. 
If the dates cannot be determined from the maintenance records, using 
the ``Date MFD'', which is located on the helicopter data plate, would 
be used as the installation date for the push-pull rods. The proposed 
AD would also require a visual inspection for corrosion on the exterior 
and interior of the three push-pull rods, part number (P/N) 28-16253-
all dash numbers (for Model F-28A, F-28C, F-28F, 280, 280C, 280F, and 
280FX helicopters) or P/N 4140532-all dash numbers (for Model TH-28, 
480, and 480B helicopters), using the compliance times stated in the 
following table. Replacing any push-pull rod that has corrosion that is 
severe enough to cause pitting or has moisture inside the rod, and 
repairing any push-pull rod that has corrosion but no pitting, would be 
required before further flight. Repairing a push-pull rod consists of 
cleaning the push-pull rod, applying a protective coating, and sealing 
the push-pull rod before reinstalling it on a helicopter.

[[Page 670]]



------------------------------------------------------------------------
                                  Push-pull rod
      Helicopter models           service life        Compliance times
------------------------------------------------------------------------
Model F-28A, F-28C, F-28F,    Push-pull rod that    Inspect within 10
 280, 280C, 280F, and 280FX    has been installed    hours time-in-
 helicopters.                  for 20 or more        service (TIS) or at
                               years.                next annual
                                                     inspection,
                                                     whichever occurs
                                                     first.
Model F-28A, F-28C, F-28F,    Push-pull rod that    Inspect within 50
 280, 280C, 280F, and 280FX    has been installed    hours TIS or at the
 helicopters.                  for 10 or more        next annual
                               years, but less       inspection,
                               than 20 years.        whichever occurs
                                                     first.
Model F-28A, F-28C, F-28F,    Push-pull rod that    Inspect before the
 280, 280C, 280F, and 280FX    has been installed    service life of the
 helicopters.                  for less than 10      push-pull rod
                               years.                reaches 10 years
                                                     since initial
                                                     installation.
Model TH-28, 480, and 480B    Push-pull rod that    Inspect within 50
 helicopters.                  has been installed    hours TIS or at the
                               for 10 or more        next annual
                               years.                inspection,
                                                     whichever occurs
                                                     first.
Model TH-28, 480, and 480B    Push-pull rod that    Inspect before the
 helicopters.                  has been installed    service life of the
                               for less than 10      push-pull rod
                               years.                reaches 10 years
                                                     since initial
                                                     installation.
------------------------------------------------------------------------

    This proposal is prompted by one reported incident in which severe 
in-flight vibrations required an emergency landing. Upon landing, the 
tail rotor, tail rotor gearbox, and horizontal stabilizer separated 
from the helicopter. A subsequent investigation revealed a rupture of 
the lower end of one of the three push-pull rods. The actions specified 
by the proposed AD are intended to detect corrosion on a push-pull rod 
and prevent failure of a push-pull rod, and subsequent loss of control 
of the helicopter.
    We have reviewed the following service information:
    <bullet> Enstrom Helicopter Corporation Service Directive Bulletin 
No. 0096, dated September 10, 2003, which describes visually inspecting 
the push-pull rods for corrosion and internal moisture, provides for 
repairing light corrosion, and is applicable to Model F-28A, F-28C, F-
28F, 280, 280C, 280F, and 280FX helicopters.
    <bullet> Enstrom Helicopter Corporation Service Directive Bulletin 
No. T-019, dated September 10, 2003, which describes visually 
inspecting the push-pull rods for corrosion and internal moisture, 
provides for repairing light corrosion, and is applicable to Model TH-
28, 480, and 480B helicopters.
    <bullet> Enstrom Helicopter Corporation Service Information Letter 
(SIL) No. T-019, dated December 9, 2003, applicable to Model TH-28, 
480, and 480B helicopters, which describes visually inspecting each 
push-pull rod for a crack, nick, scratch, dent, corrosion, damaged 
threads, bending, and contact wear. We are not proposing to require the 
inspections specified in the SIL.
    <bullet> Enstrom Helicopter Corporation Service Information Letter 
No. 0156, dated December 9, 2005, applicable to Model F-28A, F-28C, F-
28F, 280, 280C, 280F, and 280FX helicopters, which describes visually 
inspecting each push-pull rod for a crack, nick, scratch, dent, 
corrosion, damaged threads, bending, and contact wear. We are not 
proposing to require the inspections specified in the SIL.
    This unsafe condition is likely to exist or develop on other 
helicopters of the same type designs. Therefore, the proposed AD would 
require determining the installation date for the push-pull rods and 
inspecting each of the three push-pull rods for corrosion. If corrosion 
that is severe enough to cause pitting is found, or if moisture is 
visible on the inside of a push-pull rod, the AD would require 
replacing the push-pull rod. If there is corrosion without pitting on a 
push-pull rod, that push-pull rod may be repaired. Repairing a push-
pull rod consists of cleaning the push-pull rod, applying a protective 
coating, and sealing the push-pull rod before remarking it and 
reinstalling it on a helicopter. The actions would be required to be 
accomplished in accordance with the specified portions of the Enstrom 
service directive bulletins described previously.
    We estimate that this proposed AD would affect 378 helicopters of 
U.S. registry, and that the required actions would take the following 
numbers of work hours to accomplish on each helicopter at an average 
labor rate of $80 per work hour:
    <bullet> 8 work hours to remove, disassemble, and inspect the 3 
push-pull rods;
    <bullet> 9 work hours to repair corrosion without pitting, remark 
each push-pull rod, and reassemble each push-pull rod; and
    <bullet> 3 work hours to reinstall 3 push-pull rods on the 
helicopter. Required parts would cost approximately $900 per 
helicopter. Based on these figures, the total cost impact of the 
proposed AD on U.S. operators would be $945,000 ($2,500 per 
helicopter), assuming 3 push-pull rods are replaced on each helicopter.

Regulatory Findings

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. Additionally, this proposed 
AD would 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 proposed 
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 a draft economic evaluation of the estimated costs to 
comply with this proposed AD. See the DMS to examine the draft 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, Safety.

[[Page 671]]

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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 
to read as follows:

Enstrom Helicopter Company: Docket No. FAA-2006-26771; Directorate 
Identifier 2005-SW-07-AD.

    Applicability: Model F-28A, F-28C, and F-28F helicopters, 
excluding serial number (S/N) 816 and subsequent; Model 280, 280C, 
280F, and 280FX helicopters, excluding S/N 2100 and subsequent; and 
Model TH-28, 480, and 480B helicopters, excluding S/N 5058 and 
subsequent, certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To detect corrosion and prevent failure of a main rotor push-
pull control rod (push-pull rod), and subsequent loss of control of 
the helicopter, accomplish the following:
    (a) Within 10 hours time-in-service (TIS) or at the next annual 
inspection, whichever occurs first, review the helicopter 
maintenance records and determine the date that each push-pull rod, 
part number (P/N) 28-16253-all dash numbers (for Model F-28A, F-28C, 
F-28F, 280, 280C, 280F, and 280FX helicopters) and P/N 4140532-all 
dash numbers (for Model TH-28, 480, and 480B helicopters), was 
installed. If the date cannot be determined from the maintenance 
records, use the ``Date MFD'', which is located on the helicopter 
data plate, as the installation date for the push-pull rod.
    (b) For Model F-28A, F-28C, F-28F, 280, 280C, 280F, and 280FX 
helicopters, using the compliance times stated in Table 1 of this 
AD, visually inspect the exterior and interior of each of the three 
push-pull rods for corrosion severe enough to cause pitting or any 
moisture, paying special attention to the area of the lower fitting, 
in accordance with section 5.1., INSPECTION, in Enstrom Helicopter 
Corporation Service Directive Bulletin No. 0096, dated September 10, 
2003 (SDB 0096).

                                 Table 1
------------------------------------------------------------------------
                                  Push-pull rod
      Helicopter models           service life        Compliance times
------------------------------------------------------------------------
Model F-28A, F-28C, F-28F,    Push-pull rod that    Inspect within 10
 280, 280C, 280F, and 280FX    has been installed    hours time-in-
 helicopters.                  for 20 or more        service (TIS) or at
                               years.                next annual
                                                     inspection,
                                                     whichever occurs
                                                     first.
Model F-28A, F-28C, F-28F,    Push-pull rod that    Inspect within 50
 280, 280C, 280F, and 280FX    has been installed    hours TIS or at the
 helicopters.                  for 10 or more        next annual
                               years, but less       inspection,
                               than 20 years.        whichever occurs
                                                     first.
Model F-28A, F-28C, F-28F,    Push-pull rod that    Inspect before the
 280, 280C, 280F, and 280FX    has been installed    service life of the
 helicopters.                  for less than 10      push-pull rod
                               years.                reaches 10 years
                                                     since initial
                                                     installation.
------------------------------------------------------------------------

    (1) Before further flight, if corrosion without pitting is found 
on a push-pull rod, then repair, reassemble, remark, and reinstall 
it in accordance with section 5.2., REPAIR/REASSEMBLY, in SDB 0096.
    (2) Before further flight, if corrosion is found that is severe 
enough to cause pitting, or if any moisture is visible on the inside 
of a push-pull rod, replace it with an airworthy push-pull rod.

    Note 1: Determining continued serviceability of the push-pull 
rods by inspecting the exterior only of each push-pull rod is 
described in Enstrom Helicopter Corporation Service Information 
Letter No. 0156, dated December 9, 2003.

    (c) For Model TH-28, 480 and 480B helicopters, using the 
compliance times stated in Table 2 of this AD, visually inspect the 
exterior and interior of each of the three push-pull rods for 
corrosion severe enough to cause pitting or any moisture, paying 
special attention to the area of the lower fitting, in accordance 
with section 5.1., INSPECTION, in Enstrom Helicopter Corporation 
Service Directive Bulletin No. T-019, dated September 10, 2003 (SDB 
T-019).

                                 Table 2
------------------------------------------------------------------------
                                  Push-pull rod
      Helicopter models           service life        Compliance times
------------------------------------------------------------------------
Model TH-28, 480, and 480B    Push-pull rod that    Inspect within 50
 helicopters.                  has been installed    hours TIS or at the
                               for 10 or more        next annual
                               years.                inspection,
                                                     whichever occurs
                                                     first.
Model TH-28, 480, and 480B    Push-pull rod that    Inspect before the
 helicopters.                  has been installed    service life of the
                               for less than 10      push-pull rod
                               years.                reaches 10 years
                                                     since initial
                                                     installation.
------------------------------------------------------------------------


[[Page 672]]

    (1) Before further flight, if corrosion without pitting is found 
on a push-pull rod, then repair, reassemble, remark, and reinstall 
it in accordance with section 5.2., REPAIR/REASSEMBLY, in SDB T-019.
    (2) Before further flight, if corrosion is found that is severe 
enough to cause pitting, or if any moisture is visible on the inside 
of a push-pull rod, replace it with an airworthy push-pull rod.

    Note 2: Determining continued serviceability of the push-pull 
rods by inspecting the exterior only of each push-pull rod is 
described in Enstrom Helicopter Corporation Service Information 
Letter No. T-019, dated December 9, 2003.

    (d) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Contact Chicago Aircraft Certification Office, Small Airplane 
Directorate, FAA, for information about previously approved 
alternative methods of compliance.

    Issued in Fort Worth, Texas, on December 26, 2006.
David A. Downey,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. E7-43 Filed 1-5-07; 8:45 am]
BILLING CODE 4910-13-P