[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
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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 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
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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]
BILLING CODE 4910-13-U
