[Federal Register Volume 59, Number 141 (Monday, July 25, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-17996]


[[Page Unknown]]

[Federal Register: July 25, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-SW-16-AD; Amendment 39-8979; AD 94-15-08]

 

Airworthiness Directives; Robinson Helicopter Company Model R22 
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 Model R22 helicopters. 
This action requires an initial inspection and repetitive checks and 
visual inspections for corrosion and cracks on certain main rotor 
blades. This amendment is prompted by reports of chordwise cracks found 
in the main rotor blades. The actions specified in this AD are intended 
to prevent abnormal in-flight vibrations, failure of the main rotor 
blade, and subsequent loss of control of the helicopter.

DATES: Effective August 9, 1994.
    Comments for inclusion in the Rules Docket must be received on or 
before September 23, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Assistant Chief Counsel, Attention: 
Rules Docket No. 93-SW-16-AD, 2601 Meacham Boulevard, Room 663, Fort 
Worth, Texas 76137.

FOR FURTHER INFORMATION CONTACT:
Ms. Lirio Liu, Aerospace Engineer, Los Angeles Aircraft Certification 
Office, FAA, Transport Airplane Directorate, 3229 East Spring Street, 
Long Beach, California 90806-2425, telephone (310) 988-5229, fax (310) 
988-5210.

SUPPLEMENTARY INFORMATION: This amendment adopts a new airworthiness 
directive that is applicable to Robinson Helicopter Company Model R22 
helicopters equipped with main rotor blades, part number (P/N) A016-2, 
with serial numbers (S/N) up to and including 7569 (all suffixes), that 
have over 500 hours time-in-service (TIS) or more than 1 year TIS. The 
manufacturer reports finding two main rotor blades with cracks caused 
by corrosion on the main rotor blade skins. The cracks started at the 
trailing edge on both the upper and lower surfaces and extended several 
inches in the chordwise direction. The FAA has determined that 
corrosion or cracks in the main rotor blade skins create an unsafe 
condition. This condition, if not corrected, could result in abnormal 
in-flight vibrations, failure of the main rotor blade, and subsequent 
loss of control of the helicopter.
    The FAA has reviewed Robinson Helicopter Company Service Bulletin 
(SB) #72, dated March 29, 1993, that describes procedures for a visual 
pilot check for corrosion or cracks in the skin of the main rotor 
blade, after the onset of any unusual vibrations, or within 25 hours 
TIS; and, thereafter at intervals of 4 months TIS. After reviewing the 
available data, the FAA has determined that repetitive visual 
inspections should be performed by a mechanic at intervals of 100 hours 
TIS, and the repetitive visual owner/operator (pilot) checks should be 
performed at intervals of 25 hours TIS.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other Robinson Helicopter Company Model R22 
helicopters of the same type design, this AD is being issued to prevent 
abnormal in-flight vibrations, failure of the main rotor blade, and 
subsequent loss of control of the helicopter. This AD requires an 
initial visual inspection by a certificated mechanic, (1) for main 
rotor blades that have less than 500 hours TIS and have been installed 
for less than 1 year, upon or prior to the accumulation of 525 hours 
TIS or upon or prior to the main rotor blades having been installed for 
1 year, whichever is earlier, or (2) for main rotor blades with 500 or 
more hours TIS or that have been installed for 1 year or more within 
the next 25 hours TIS. The inspection threshold is 1 year and 500 hours 
TIS. Thereafter, inspections for corrosion and cracks are required at 
intervals of not more than 100 hours TIS, or before further flight 
after the onset of abnormal vibrations. This AD also requires 
repetitive checks for corrosion and cracks in the main rotor blade at 
intervals not to exceed 25 hours TIS. These checks may be performed by 
an owner/operator holding at least a private pilot certificate but must 
be documented in the aircraft records showing compliance with this AD 
in accordance with sections 43.11 and 91.417(a)(2)(v) of the Federal 
Aviation Regulations. These checks do not require the use of tools, 
precision measuring equipment, training, pilot logbook endorsements, or 
the use of technical data not contained in the AD. These 25 hours TIS 
checks are additional measures to ensure that a crack that is visible 
without the aid of a magnifying glass has not developed during the time 
between maintenance inspections. However, this AD does not require 
visual checks at intervals of 4 months as specified by the SB, dated 
March 29, 1993. Due to the criticality of the main rotor blades and the 
short compliance times, this rule must be issued immediately to correct 
an unsafe condition in aircraft.
    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 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 notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 93-SW-16-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.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

AD 94-15-08 Robinson Helicopter Company: Amendment 39-8979. Docket 
Number 93-SW-16-AD.

    Applicability: Model R22 helicopters, equipped with main rotor 
blades, part number (P/N) A016-2, with serial numbers (S/N) up to 
and including 7569 (including any suffixes), certificated in any 
category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent abnormal in-flight vibrations, failure of a main 
rotor blade (blade), and subsequent loss of control of the 
helicopter, accomplish the following:
    (a) For blades that have less than 500 hours time-in-service 
(TIS) and have been installed on a helicopter for less than 1 year, 
visually inspect the blades' top and bottom skins for corrosion or 
cracks using a 5-power or higher magnifying glass in accordance with 
the applicable maintenance manual. Conduct this visual inspection 
upon or prior to the accumulation of 525 hours TIS or upon or prior 
to the blades being installed for 1 year, whichever occurs first.
    (b) For blades that have 500 or more hours TIS or have been 
installed on a helicopter for 1 year or more, within the next 25 
hours TIS visually inspect the blades' top and bottom skins for 
corrosion or cracks using a 5-power or higher magnifying glass in 
accordance with the applicable maintenance manual.
    (c) After the initial visual inspection required by paragraph 
(a) or (b), conduct the following inspections and checks:
    (1) Visually inspect the blades' top and bottom skins for 
corrosion or cracks using a 5-power or higher magnifying glass at 
intervals not to exceed 100 hours TIS from the last inspection 
required by this AD.
    (2) Visually check the blades' top and bottom skins for 
corrosion or cracks at intervals not to exceed 25 hours TIS from the 
last check or inspection required by this AD. The visual checks 
required by this AD may be performed by an owner/operator holding at 
least a private pilot certificate, and must be documented in the 
aircraft records showing compliance with this AD, in accordance with 
sections 43.11 and 91.417(a)(2)(v) of the Federal Aviation 
Regulations.
    (d) Before further flight after the onset of abnormal vibrations 
of the main rotor system, visually inspect the blades' top and 
bottom skins for corrosion or cracks using a 5-power or higher 
magnifying glass.
    (e) If a suspected crack is found in a blade during the 
inspections or checks required by this AD, conduct a dye penetrant 
or equivalent FAA-approved inspection for crack verification.
    (f) If any crack is found in the blade skins, replace the blade 
with an airworthy blade before further flight.
    (g) If any corrosion is found in the blade skins, repair or 
replace the blade with an airworthy blade in accordance with the 
provisions of the maintenance manual.

    Note: Robinson Helicopter Company Service Bulletin #72, dated 
March 29, 1993, pertains to this AD.

    (h) 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 an FAA Principal Maintenance Inspector, who may concur or 
comment and then send it to the Manager, Los Angeles Aircraft 
Certification Office.

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

    (i) Special flight permits to comply with this AD will not be 
issued.
    (j) This amendment becomes effective on August 9, 1994.

    Issued in Fort Worth, Texas, on July 14, 1994.
James D. Erickson,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 94-17996 Filed 7-22-94; 8:45 am]
BILLING CODE 4910-13-M