Airworthiness Directives; Robinson Helicopter Company Model R44 Helicopters

[Federal Register Volume 62, Number 148 (Friday, August 1, 1997)]
[Rules and Regulations]
[Pages 41260-41262]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-20195]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-SW-19-AD; Amendment 39-10092; AD 97-16-02]
RIN 2120-AA64


Airworthiness Directives; Robinson Helicopter Company Model R44 
Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to Robinson Helicopter Company (Robinson) Model R44 
helicopters. This action requires inspections of the belt tension 
actuator switches (up-limit switches) for proper

[[Page 41261]]

operation, and replacement if necessary; and replacement of a certain 
part-numbered clutch assembly. This amendment is prompted by six 
occurrences of prematurely worn sprag clutches. The actions specified 
in this AD are intended to prevent failure of the sprag clutch to lock 
in the driving direction, which would result in loss of power to the 
main rotor system and a subsequent forced landing; or failure of the 
sprag clutch to unlock in the overrunning direction, which, if combined 
with engine failure, would result in an inability to autorotate and a 
subsequent loss of control of the helicopter.

DATES: Effective August 18, 1997.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of August 18, 1997.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of August 18, 1997.
    Comments for inclusion in the Rules Docket must be received on or 
before September 30, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Assistant Chief Counsel, Attention: 
Rules Docket No. 97-SW-19-AD, 2601 Meacham Blvd., Room 663, Fort Worth, 
Texas 76137.
    The service information referenced in this AD may be obtained from 
Robinson Helicopter Company, 2901 Airport Drive, Torrance, California 
90505, telephone (310) 539-0508, fax (310) 539-5198. This information 
may be examined at the FAA, Office of the Assistant Chief Counsel, 2601 
Meacham Blvd., Room 663, Fort Worth, Texas 76137; or at the Office of 
the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.

FOR FURTHER INFORMATION CONTACT: Ms. Elizabeth Bumann, Aerospace 
Engineer, FAA, Los Angeles Aircraft Certification Office, Propulsion 
Branch, 3960 Paramount Blvd., Lakewood, California 90712, telephone 
(562) 627-5265, fax (562) 627-5210.

SUPPLEMENTARY INFORMATION: This amendment adopts a new Airworthiness 
Directive (AD), which is applicable to Robinson Model R44 helicopters 
and requires, within 25 hours time-in-service (TIS) after the effective 
date of this AD and thereafter at intervals not to exceed 100 hours 
TIS, an inspection of both up-limit switches, part number (P/N) V3-
1001, for proper operation, and replacement of either switch, if 
necessary. Additionally, this AD requires, within 50 hours TIS after 
the effective date of this AD, replacement of the clutch assembly, P/N 
C018-1, with clutch assembly, P/N C018-2 or P/N C018-2A. This AD is 
prompted by six occurrences of prematurely worn sprag clutches. Five of 
those clutch assemblies' hours TIS ranged from 286.3 to 828.6 hours 
TIS. All of the clutch assemblies were making noise during the landings 
and/or shutdowns. One clutch assembly would not allow the main rotor to 
disengage from the engine during a practice autorotation. Excessive 
wear of the sprag crowns and chattering of the sprag races causes 
erratic operation of the clutch by preventing the sprags from rolling 
into or releasing from the locked position. A latent failure of one up-
limit switch can exist undetected, eliminating the redundancy of the 
system. A failure of both up-limit switches while in the closed 
position will result in over-tensioning of the drive belts. The actions 
specified in this AD are intended to prevent failure of the sprag 
clutch to lock in the driving direction, which would result in loss of 
power to the main rotor system and a subsequent forced landing; or 
failure of the sprag clutch to unlock in the overrunning direction, 
which, if combined with engine failure, would result in an inability to 
autorotate and a subsequent loss of control of the helicopter.
    The FAA has reviewed Robinson Helicopter Company R44 Service 
Bulletin SB-21, dated April 18, 1997, which describes procedures for 
removing the aft engine cowling and inspecting to verify that both up-
limit switches function properly. If either up-limit switch does not 
function properly, the service bulletin refers the reader to the 
replacement procedures in the maintenance manual. The FAA has also 
reviewed Robinson Helicopter Company R44 Service Bulletin SB-23, dated 
May 30, 1997, which describes or refers to the appropriate procedures 
for replacing clutch assembly, P/N C018-1. The compliance times of this 
AD differ from those stated in the service bulletins. Robinson 
Helicopter Company R44 Service Bulletin SB-21 describes a one-time 
inspection within the next 10 hours TIS, or by April 30, 1997, 
whichever occurs first; this AD requires an initial inspection within 
25 hours TIS after the effective date of this AD, and thereafter, 
repetitive inspections at intervals not to exceed 100 hours TIS. 
Robinson Helicopter Company R44 Service Bulletin SB-23 describes 
replacing the clutch assembly within the next 100 hours TIS, or by 
September 30, 1997, whichever occurs first; this AD requires replacing 
the clutch assembly within 50 hours TIS after the effective date of 
this AD, since the only indication of excessive sprag clutch wear is 
hard or rough engagement of the clutch, which may be difficult for a 
pilot to detect. The failure of the clutch assembly to allow the main 
rotor system to disengage from the engine in the event of an engine 
failure creates a significant unsafe condition in that this condition 
would result in an inability to autorotate.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other Robinson Model R44 helicopters of the same 
type design, this AD is being issued to prevent failure of the sprag 
clutch to lock in the driving direction, which will result in loss of 
power to the main rotor and a subsequent forced landing; or failure of 
the sprag clutch to unlock in the overrunning direction, which, if 
combined with engine failure, could result in catastrophic loss of the 
helicopter since the main rotor cannot be disengaged from the engine 
for autorotation.
    This AD requires both initial and repetitive inspections of the up-
limit switches, P/N V3-1001, to determine that they are functioning 
properly, and replacement of either up-limit switch, if necessary; and 
replacement of the clutch assembly, P/N C018-1 with clutch assembly, P/
N C018-2 or P/N C018-2A. The actions are required to be accomplished in 
accordance with the compliance procedures contained in the service 
bulletins described previously.
    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.

Comments Invited

    Although this action is in the 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 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 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

[[Page 41262]]

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.
    Commenters 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. 97-SW-19-AD.'' The postcard will be date 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, 1979). 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.

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:

97-16-02  Robinson Helicopter Company: Amendment 39-10092. Docket 
No. 97-SW-19-AD.

    Applicability: Model R44 helicopters, serial numbers 0001 
through 0332, 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 (d) 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 as indicated, unless accomplished 
previously.
    To prevent failure of the sprag clutch to lock in the driving 
direction, which would result in loss of power to the main rotor 
system and a subsequent forced landing; or failure of the sprag 
clutch to unlock in the overrunning direction, which, if combined 
with engine failure, would result in an inability to autorotate and 
a subsequent loss of control of the helicopter, accomplish the 
following:
    (a) Within 25 hours time-in-service (TIS) after the effective 
date of this AD, and thereafter, at intervals not to exceed 100 
hours TIS, inspect both up-limit switches, part number (P/N) V3-
1001, for proper operation in accordance with the Compliance 
Procedure in Robinson Helicopter Company R44 Service Bulletin SB-21, 
dated April 18, 1997. If the motor runs when the springs are 
depressed on one side, the switch on the OPPOSITE side is not 
functioning properly.
    (b) If the inspections required by paragraph (a) of this AD 
indicate that either up-limit switch does not function properly, 
replace the up-limit switch with an airworthy up-limit switch in 
accordance with the Compliance Procedure contained in Robinson 
Helicopter Company R44 Service Bulletin SB-21, dated April 18, 1997.
    (c) Within 50 hours TIS after the effective date of this AD, 
replace the clutch assembly, P/N C018-1, with a clutch assembly, P/N 
C018-2 or P/N C018-2A, in accordance with the Compliance Procedure 
contained in Robinson Helicopter Company R44 Service Bulletin SB-23, 
dated May 30, 1997.
    (d) 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, Los Angeles Aircraft 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, 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.

    (e) 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.
    (f) The inspections and replacements, if necessary, shall be 
done in accordance with Robinson Helicopter Company R44 Service 
Bulletin SB-21, dated April 18, 1997, and Robinson Helicopter 
Company R-44 Service Bulletin SB-23, dated May 30, 1997. 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 Robinson Helicopter Company, 2901 
Airport Drive, Torrance, California 90505, telephone (310) 539-0508, 
fax (310) 539-5198. Copies may be inspected at the FAA, Office of 
the Assistant Chief Counsel, 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.
    (g) This amendment becomes effective on August 18, 1997.

    Issued in Fort Worth, Texas, on July 22, 1997.
Mark R. Schilling,
Acting Manager, Rotercraft Directorate, Aircraft Certification Service.
[FR Doc. 97-20195 Filed 7-31-97; 8:45 am]
BILLING CODE 4910-13-U

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