[Federal Register Volume 64, Number 66 (Wednesday, April 7, 1999)]
[Rules and Regulations]
[Pages 16801-16803]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-8407]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-SW-16-AD; Amendment 39-11111; AD 99-06-15]
RIN 2120-AA64


Airworthiness Directives; Bell Helicopter Textron Canada Model 
407 Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This document publishes in the Federal Register an amendment 
adopting Airworthiness Directive (AD) 99-06-15 which was sent 
previously to all known U.S. owners and operators of Bell Helicopter 
Textron Canada (BHTC) Model 407 helicopters by individual letters. This 
AD requires installing a tail rotor pitch-limiting left-pedal stop, 
installing an airspeed limitation placard, marking a never-exceed 
velocity (Vne) placard on all airspeed indicators, and revising the 
Limitations section of the Rotorcraft Flight Manual (RFM). This 
amendment is prompted by three accidents involving inflight tail rotor 
blade strikes against the tailboom. The actions specified by this AD 
are intended to prevent the tail rotor blades from striking the 
tailboom, which could result in separation of the aft section of the 
tailboom with the tail rotor gearbox and vertical fin, and subsequent 
loss of control of the helicopter.

DATES: Effective April 22, 1999, to all persons except those persons to 
whom it was made immediately effective by Priority Letter AD 99-06-15, 
issued on March 9, 1999, which contained the requirements of this 
amendment.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of April 22, 1999.
    Comments for inclusion in the Rules Docket must be received on or 
before June 7, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 99-SW-16-AD, 2601 Meacham Blvd., Room 663, 
Fort Worth, Texas 76137.
    The applicable service information may be obtained from Bell 
Helicopter Textron Canada, 12,800 Rue de l'Avenir, Mirabel, Quebec 
JON1LO, telephone (800) 463-3036, fax (514) 433-0272. This information 
may be examined 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.

FOR FURTHER INFORMATION CONTACT: Jurgen Priester, Aerospace Engineer, 
FAA, Rotocraft Directorate, Rotorcraft Certification Office, ASW-170, 
2601 Meacham Blvd., Fort Worth, Texas, 76137, telephone (817) 222-5159, 
fax (817) 222-5783.

SUPPLEMENTARY INFORMATION: On September 25, 1998, the FAA issued 
Priority Letter AD 98-20-41, applicable to BHTC Model 407 helicopters, 
which restricted the airspeed to 25 knots indicated airspeed less than 
the Vne airspeeds indicated on the airspeed limitation placard. The 
priority letter also required installing an airspeed limitation 
placard, marking a redline at a Vne of 115 knots and applying a red arc 
from 115 to 140 knots on all airspeed indicators, and revising the 
Limitations section of the RFM that requires pilots to maintain yaw 
trim within one ball width of the centered position of the turn and 
bank (slip) indicator. That action was prompted by two accidents 
involving in-flight tail rotor blade strikes against the tailboom on 
Model 407 helicopters. Persons aboard both helicopters reported hearing 
a loud ``bang'' immediately prior to experiencing a loss of directional 
control of the helicopter. Subsequent inspection of the helicopters 
revealed that the aft section of the tailboom, including the tail 
rotor, the tail rotor gearbox, and the vertical fin, had separated from 
the helicopters in-flight. In both cases, inspection of the retrieved 
tailbooms confirmed that the tailbooms had been struck at least three 
times by the rotating tail rotor blades. The specific cause of these 
two in-flight tail rotor blade strikes against the tailboom has not 
been determined; however, flight test data indicated that tail rotor 
blade strikes were more likely to occur at higher airspeeds and 
altitudes. The data indicated that the cause of the tail rotor strikes 
is excessive tail rotor blade flapping. The reason for the excessive 
tail rotor blade flapping is unknown, but it may be aggravated by left 
pedal input. Excessive tail rotor flapping, if not corrected, could 
result in the tail rotor blades striking the tailboom, separation of 
the aft section of the tailboom with the tail rotor gearbox and 
vertical fin, and subsequent loss of control of the helicopter. 
Transport Canada, which is the airworthiness authority for Canada, 
issued AD CF-98-36, dated September 25, 1998, to require that the 
airspeed be reduced to minimize the risk of a tailboom strike during 
flight. After the issuance of Priority Letter AD 98-20-41, BHTC issued 
Technical Bulletin No. 407-98-13, dated December 12, 1998 (TB), which 
recommended a reduction in Vne of only 15 KIAS with the installation of 
a left pedal stop to limit maximum tail rotor blade pitch
    Transport Canada then further notified the FAA that an unsafe 
condition may continue to exist on BHTC Model 407 helicopters. 
Transport Canada advised that installing the tail rotor pitch-limiting 
left-pedal stop in accordance with the TB and further reducing the Vne 
is required to minimize the risk of a tailboom strike during flight. 
Transport Canada classified the TB as mandatory, and issued AD CF-98-
36R3, dated March 5, 1999, in order to assure the continued 
airworthiness of these helicopters in Canada. That action was prompted 
by a third accident involving an in-flight tail rotor blade strike 
against the tailboom on BHTC Model 407 helicopters. The pilot in this 
latest accident reported that the helicopter was in straight and level 
cruise flight at 110 KIAS in non-turbulent conditions when the

[[Page 16802]]

helicopter experienced an uncommanded left pedal hardover. The pilot 
reported that this uncommanded full left pedal movement was followed by 
a loud ``bang'' and then a loss of directional control of the 
helicopter. Subsequent inspection of the helicopter revealed that the 
aft section of the tailboom, including the tail rotor, the tail rotor 
gearbox, and the vertical fin, had separated from the helicopter in-
flight. This helicopter did not have the tail rotor pitch-limiting 
left-pedal stop installed.
    Since the unsafe condition described is likely to exist or develop 
on other BHTC Model 407 helicopters of the same type design, the FAA 
issued Priority Letter AD 99-06-15 to supersede Priority Letter AD 98-
20-41. Priority Letter AD 99-06-15 requires, before further flight, 
installing a tail rotor pitch-limiting left-pedal stop and adjusting 
the rigging of the directional controls, installing a new airspeed 
limitation placard, marking a new Vne limit of 100 knots indicated 
airspeed on all airspeed indicators, and revising the RFM to reduce the 
airspeed limitation further and to maintain the previously revised yaw-
operational limitations. The priority letter AD is intended to prevent 
the tail rotor blades from striking the tailboom, which could result in 
separation of the aft section of the tailboom with the tail rotor 
gearbox and vertical fin, and subsequent loss of control of the 
helicopter. The actions specified by the superseding priority letter AD 
are required to be accomplished in accordance with the TB described 
previously. The short compliance time involved is required because the 
previously described critical unsafe condition can adversely affect the 
structural integrity of the helicopter. Therefore, installing a tail 
rotor pitch-limiting left-pedal stop, installing a new airspeed 
limitation placard, marking a new Vne limit on all airspeed indicators, 
and revising the RFM are required prior to further flight, and this AD 
must be issued immediately.
    Since it was found that immediate corrective action was required, 
notice and opportunity for prior public comment thereon were 
impracticable and contrary to the public interest, and good cause 
existed to make the AD effective immediately by individual letters 
issued on March 9, 1999 to all known U.S. owners and operators of BHTC 
Model 407 helicopters. These conditions still exist, and the AD is 
hereby published in the Federal Register as an amendment to section 
39.13 of the Federal Aviation Regulations (14 CFR 39.13) to make it 
effective to all persons.
    The FAA estimates that 200 helicopters of U.S. registry will be 
effected by this AD, that it will take approximately 2 work hours per 
helicopter to accomplish the required actions, and the average labor 
rate is $60 per work hour. Required parts will cost approximately $245 
per helicopter. Based on these figures the total cost impact of the AD 
on U.S. operators is estimated to be $73,000.

Comments Invited

    Although this action is in 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 
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.
    Comments 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. 99-SW-16-AD.'' The postcard will be 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, 1997). 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 
to read as follows:

AD 99-06-15 Bell Helicopter Textron Canada: Amendment 39-11111. 
Docket No. 99-SW-16-AD.

    Applicability: Model 407 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 
otherwise 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 request approval for an 
alternative method of compliance in accordance with paragraph (i) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.


[[Page 16803]]


    Compliance: Required before further flight, unless accomplished 
previously.
    To prevent the tail rotor blades from striking the tailboom, 
which could result in separation of the aft section of the tailboom 
with the tail rotor gearbox and vertical fin, and subsequent loss of 
control of the helicopter, accomplish the following:
    (a) Install a stop that limits the maximum distance that the 
left pedal can travel in accordance with Part I of the 
Accomplishment Instructions in Bell Helicopter Textron Canada 
Technical Bulletin 407-98-13, dated December 12, 1998 (TB).
    (b) Adjust the rigging of the directional controls in accordance 
with Part II of the Accomplishment Instructions in the TB.
    (c) Install the airspeed limitation placard shown in Figure 1 of 
this AD so that it completely covers and obscures the airspeed 
limitation placard, P/N 407-070-201-103. Ensure that the replacement 
placard is at least 2\1/16\-inches tall and 3\9/16\-inches long.

                                                       Figure.--407 Airspeed Limitations-Knots-IAS
                                                                      [AD 99-06-15]
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                                                            Maximum Autorotation VNE 100 KIAS
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                    OAT                                                              Pressure Altitude FT X 1000
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                  C deg.                        0         2         4         6         8        10        12        14        16        18        20
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52........................................        98        93        88  ........  ........  ........  ........  ........  ........  ........  ........
40........................................       100        95        91        86        81        76  ........  ........  ........  ........  ........
20........................................       100       100        95        90        85        80        76        71        66        61  ........
0.........................................       100       100       100        95        90        85        80        75        70        65        60
-20.......................................       100       100       100       100        95        90        85        80        75        70        65
-40.......................................        97        93        88        83        79        74        70        65        61  ........  ........
--------------------------------------------------------------------------------------------------------------------------------------------------------

    (d) Install a redline at a Vne of 100 KIAS on all airspeed 
indicators. Remove or obscure any previously installed lines or 
acrcs above 100 KIAS. If the redline is installed on the instrument 
glass, also install a slippage mark on the glass and on the 
isntrument case.
    (e) Add the following statement to the Limitations section of 
the Rotorcraft Flight Manual (RFM): When operating at an airspeed of 
60 to 100 KIAS, maintain yaw trim within one ball diameter of the 
centered position of the turn and bank (slip) indicator, and avoid 
sudden or large directional control inputs in flight.
    (f) Mark the airspeed limitations placard in Figure 1-3 in the 
RFM to indicate that it has been superseded by this AD, and insert a 
copy of this AD into the RFM. Also, mark the airspeed indicator in 
Figure 1-5 of the RFM to indicate a Vne of 100 KIAS.
    (g) This AD revises the limitations section of BHTC Model 407 
RFM by replacing sheet 1 of Figure 1-3 in the RFM with Figure 1 of 
this AD, revising sheet 3 of Figure 1-5 of the RFM, and adding an 
operational limitation for allowable yaw trim and directional 
control input.
    (h) Report any uncommanded right yaw, uncommanded movement of 
the pedals during flight, or tail rotor blade contact with the 
tailboom within 24 hours of the occurence to the Manager, Rotorcraft 
Certification Office, telephone (817) 222-5170. Reporting 
requirements have been approved by the Office of Management and 
Budget and assigned OMB control number 2120-0056.
    (i) 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, Rotorcraft Certification Office, 
FAA. Operators shall submit their requests through an FAA Principal 
Maintenance Inspector, who may concur or comment and then send it to 
the Manager, Rotorcraft Certification Office.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Rotorcraft Certification Office.

    (j) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the helicopter to a location where 
the requirements of this AD can be accomplished, provided they are 
for a one-time ferry flight without passengers, and that airspeed 
during the flight does not exceed 60 KIAS. For helicopters with a 
left-pedal stop installed in accordance with the TB, the airspeed 
must not exceed 100 KIAS for a one-time ferry flight without 
passengers.
    (k) The modifications shall be done in accordance with Parts I 
and II of the Accomplishment Instructions in Bell Helicopter Textron 
Canada Technical Bulletin 407-98-13, dated December 12, 1998. 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 Bell Helicopter Textron Canada, 
12,800 Rue de l'Avenir, Mirabel, Quebec JON1LO, telephone (800) 463-
3036, fax (514) 433-0272. 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.
    (l) This amendment becomes effective on April 22, 1999, to all 
persons except those persons to whom it was made immediately 
effective by Priority Letter AD 99-06-15, issued March 9, 1999, 
which contained the requirements of this amendment.

    Note 3: The subject of this AD is addressed in Transport Canada 
(Canada) AD CF-98-36R3, dated March 5, 1999.

    Issued in Fort Worth, Texas, on March 30, 1999.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 99-8407 Filed 4-6-99; 8:45 am]
BILLING CODE 4910-13-M