[Federal Register Volume 60, Number 240 (Thursday, December 14, 1995)]
[Proposed Rules]
[Pages 64129-64131]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-30422]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-SW-27-AD]


Airworthiness Directives; Robinson Helicopter Company Model R22 
Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to Robinson Helicopter Company 
(Robinson) Model R22 helicopters, that currently requires installing a 
low-rotor RPM caution light and resetting the low-RPM warning unit to 
activate the warning horn and caution light at 94% to 96% revolutions-
per-minute (RPM). This action would require installation of an improved 
throttle governor; an adjustment to the warning horn threshold to 
increase the RPM at which the warning horn and caution light activate; 
and, revisions to the R22 Rotorcraft Flight Manual that prohibit flight 
with the improved throttle governor inoperative, except in certain 
situations. This proposal is prompted by an FAA Technical Panel review 
of Model R22 accident history data which revealed that main rotor (M/R) 
blade stall at abnormally low M/R RPM resulted in accidents. The 
actions specified by the proposed AD are intended to minimize the 
possibility of pilot mismanagement of the M/R RPM, which could result 
in unrecoverable M/R blade stall and subsequent loss of control of the 
helicopter.

DATES: Comments must be received by Janaury 29, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Assistant Chief Counsel, Attention: 
Rules Docket No. 95-SW-27-AD, 2601 Meacham Blvd., Room 663, Fort Worth, 
Texas 76137. Comments may be inspected at this location between 9:00 
a.m. and 3:00 p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Mr. James Wang, Helicopter Program 
Manager, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount 
Blvd., Lakewood, California 90712-4137, telephone (310) 627-5303; fax 
(310) 627-5210.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed 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 above. All 
communications received on or before the closing date for comments, 
specified 

[[Page 64130]]
above, will be considered before taking action on the proposed rule. 
The proposals contained in this notice may be changed in light of the 
comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket No. 95-SW-27-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Office of the Assistant Chief Counsel, Attention: Rules 
Docket No. 95-SW-27-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 
76137.

Discussion

    On April 28, 1983, the FAA issued AD 82-23-51, Amendment 39-4645 
(48 FR 21894, May 16, 1983), to require installing a low-rotor RPM 
caution light and resetting the low-RPM warning unit to activate the 
warning horn and caution light at 94% to 96% RPM. That action was 
prompted by several accidents involving M/R blades striking the 
helicopter tailboom in flight. Some tailboom strikes have been 
attributed to M/R blade stall at abnormally low RPM. The requirements 
of that AD are intended to provide early detection of low-rotor RPM to 
minimize the possibility of severe M/R blade flapping, which could 
result in the M/R blades striking the tailboom and subsequent loss of 
control of the helicopter.
    Since the issuance of that AD, an FAA Technical Panel review of 
Model R22 helicopter accident history data revealed that some accidents 
resulted from pilot mismanagement of the M/R RPM.
    One of the Technical Panel's recommendations was for the 
manufacturer to configure the Model R22 with an improved throttle 
governor. Robinson has incorporated the improved throttle governor on 
new production helicopters, and has made the improved throttle governor 
available as a retrofit kit for all Model R22 helicopters.
    The FAA agrees with the Technical Panel's recommendation and has 
determined that an improved throttle governor should be used to 
maintain M/R RPM, thereby decreasing the possibility of M/R blade stall 
resulting in the M/R blades striking the helicopter tailboom in flight. 
The improved throttle governor will also reduce pilot workload, 
allowing the pilot to focus more attention on other aspects of flying 
the aircraft and avoiding possible obstructions. There are four types 
of governors currently available for installation on the Model R22 
helicopters. Three are throttle/collective governor models that will 
automatically make throttle (RPM) and collective stick position (pitch) 
corrections. The fourth governor, which is the improved throttle 
governor, makes only throttle (RPM) corrections and significantly 
improves the ability to maintain M/R speed control. Some operators find 
throttle/collective governor corrections of collective stick position 
to be distracting and routinely fly with the throttle/collective 
governor selected off, thus defeating the governor's purpose of tighter 
rotor RPM control. While other operators find these throttle/collective 
governor collective stick movements acceptable, the FAA is concerned 
about the different operating characteristics and associated safety 
implications of a mixed fleet of throttle/collective and improved 
throttle governors, particularly in the training environment. The 
differences in flight operating characteristics between the throttle/
collective governor and the improved throttle governor are significant 
and could cause confusion and an unsafe condition for students and low-
time pilots when changing between Model R22 helicopters. The FAA 
therefore proposes to require the installation and use of the improved 
throttle governor to enhance the ability to maintain M/R speed control 
on all Model R22 helicopters, to eliminate possibly distracting 
collective stick position corrections on those aircraft currently 
equipped with the throttle/collective governor, and to maintain 
consistent flight operating characteristics of the Model R22 fleet.
    A second recommendation made by the Technical Panel was to increase 
the RPM at which the warning horn and caution light activate, thereby 
allowing additional time for the initiation of corrective action 
between the activation of the warning horn and caution light and the 
onset of M/R blade stall. The installation of the improved throttle 
governor will allow for this increase in the warning threshold, without 
unnecessary nuisance activations, due to the governor's ability to 
maintain tighter control of the M/R RPM.
    Based on these recommendations, Robinson issued Robinson Helicopter 
Company R22 Service Bulletin SB-80A, Revised June 8, 1995, which 
describes procedures for installation of a KI-67-2 Governor Field 
Installation Kit on certain serial-numbered Model R22 helicopters, and 
procedures for increasing the RPM threshold at which the warning horn 
and caution light activate to avoid inadvertent low M/R RPM. This 
condition, if not corrected, could result in unrecoverable M/R blade 
stall and a subsequent loss of control of the helicopter. Since the 
issuance of this service bulletin, Robinson has manufactured a KI-67-3 
Governor Upgrade Kit to incorporate the improved throttle governor on 
helicopters that have a throttle/collective governor currently 
installed.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other Robinson Model R22 helicopters of the same 
type design, the proposed AD would require: the installation of an 
improved throttle governor on certain Model R22 helicopters not 
currently equipped with a governor, or the upgrade to the improved 
throttle governor on those Model R22 helicopters currently equipped 
with a throttle/collective governor; an adjustment to the warning horn 
and caution light threshold from 95<plus-minus> 1% RPM to between 96% 
and 97% RPM to increase the RPM at which the warning activates; and 
revisions to the Robinson Helicopter Company R22 Rotorcraft Flight 
Manual prohibiting flight with the governor selected off, with 
exceptions for system malfunction and emergency procedures training 
with an instructor pilot.
    The FAA estimates that 1,014 helicopters of U.S. registry would be 
affected by this proposed AD, that it would take approximately 8 work 
hours to install the improved throttle governor, or 7 hours to upgrade 
the throttle/collective governor, and approximately 0.2 work hours to 
accomplish the adjustment of the light/warning horn RPM, and that the 
average labor rate is $60 per work hour. Required parts would cost 
approximately $2,150 per helicopter to install the improved throttle 
governor, or approximately $500 for upgrading the throttle/collective 
governor per helicopter. Based on these figures, the total cost impact 
of the proposed AD on U.S. operators is estimated to be $2,678,988. 
This cost estimate assumes that no helicopters are currently 

[[Page 64131]]
equipped with a governor and all will need the improved throttle 
governor installed.
    The regulations proposed herein would 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 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this 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) if promulgated, 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. A copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

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 USC 106(g), 40101, 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing Amendment 39-4645 (48 FR 
21894, May 16, 1983), and by adding a new airworthiness directive (AD) 
to read as follows:

Robinson Helicopter Company: Docket No. 95-SW-27-AD. Supersedes AD 
82-23-51, Amendment 39-4645.

    Applicability: Model R22 helicopters, serial numbers (S/N) 0002 
to 2537, 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 (e) 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 
case does the presence of any modification, alteration, or repair 
remove any helicopter from the applicability of this AD.

    Compliance: Required within the next 30 days after the effective 
date of this AD, unless accomplished previously.
    To minimize the possibility of pilot mismanagement of the main 
rotor (M/R) revolutions-per-minute (RPM), which could result in 
unrecoverable M/R blade stall and subsequent loss of control of the 
helicopter, accomplish the following:
    (a) Adjust the A569-1 or -5 low-RPM warning unit so that the 
warning horn and caution light activate when the M/R RPM is between 
96% and 97% rotor RPM in accordance with the procedures contained in 
the Model R22 maintenance manual.
    (b) For Model R22 helicopters that do not have a governor 
currently installed, install a Robinson Helicopter Company KI-67-2 
Governor Field Installation Kit in accordance with the kit 
instructions.
    (c) For Model R22 helicopters that have a throttle/collective 
governor currently installed, upgrade the governor with a Robinson 
Helicopter Company KI-67-3 Governor Upgrade Kit in accordance with 
the kit instructions.
    (d) Upon accomplishment of paragraph (b) or (c) of this AD, 
insert pages 2-2 and 2-7 of the FAA-approved Robinson Helicopter 
Company R22 Rotorcraft Flight Manual, revised July 6, 1995, into 
each Model R22 helicopter's flight manual, and make pen-and-ink 
changes to page 2-7 to delete the phrase ``If equipped with RPM 
governor,'' and add the phrase ``with an instructor pilot'' so that 
the affected limitation will state ``Flight prohibited with governor 
selected off, with exceptions for system malfunction and emergency 
procedures training with an instructor pilot.'' Also, delete the 
phrase ``If not equipped with RPM governor,'' so that the affected 
limitation will state ``Maximum power-on RPM required during 
takeoff, climb, or level flight below 500 feet AGL or above 5000 
feet density altitude.''
    (e) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used when approved by the Manager, Los Angeles Aircraft 
Certification Office, FAA. Operators shall submit their requests 
through FAA Principal Maintenance Inspectors, who may concur or 
comment and then send it to the Manager, Los Angeles Aircraft 
Certification Office.

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

    (f) Special flight permits may be issued in accordance with 
Secs. 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.

    Issued in Fort Worth, Texas, on December 6, 1995.
Daniel P. Salvano,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 95-30422 Filed 12-13-95; 8:45 am]
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