Airworthiness Directives; Robinson Helicopter Company (RHC) Model R44 Helicopters

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-SW-56-AD; Amendment 39-10874; AD 98-22-16]

Airworthiness Directives; Robinson Helicopter Company (RHC) Model

R44 Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

-----------------------------------------------------------------------

SUMMARY: This document publishes in the Federal Register an amendment

adopting Airworthiness Directive (AD) 98-22-16 which was sent

previously to all known U.S. owners and operators of RHC Model R44

helicopters by individual letters. This amendment supersedes AD 98-12-

19, issued August 5, 1998, applicable to RHC Model R44 helicopters,

that currently requires main rotor blade inspections and replacement if

a crack is found. This amendment requires the same inspections as AD

98-12-19, but mandates replacement of all the affected main rotor

blades prior to further flight after November 15, 1998. This amendment

is prompted by an incident in which a crack was discovered in a main

rotor blade. The actions specified by this AD are intended to prevent

failure of a main rotor blade and subsequent loss of control of the

helicopter.

DATES: Effective November 10, 1998, to all persons except those persons

to whom it was made immediately effective by priority letter AD 98-22-

16, issued on October 22, 1998, which contained the requirements of

this amendment.

Comments for inclusion in the Rules Docket must be received on or

before January 11, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Office of the Regional Counsel, Southwest Region,

Attention: Rules Docket No. 98-SW-56-AD, 2601 Meacham Blvd., Room 663,

Fort Worth, Texas 76137.

FOR FURTHER INFORMATION CONTACT: Frederick Guerin, Aerospace Engineer,

FAA, Los Angeles Aircraft Certification Office, Airframe Branch, 3960

Paramount Blvd., Lakewood, California 90712, telephone (562) 627-5232,

fax (562) 627-5210.

SUPPLEMENTARY INFORMATION: On October 22, 1998, the FAA issued priority

letter AD 98-22-16, applicable to RHC Model R44 helicopters, which

[[Page 62932]]

requires inspecting each main rotor blade for cracks every 5 hours

time-in-service (TIS) until each main rotor blade is replaced with a

redesigned main rotor blade. The main rotor blade must be replaced

prior to further flight after November 15, 1998. The AD was prompted by

an incident in which a pilot heard a loud noise and felt severe

vibrations while hovering, resulting in a forced landing. Upon

inspection, a crack was found in a main rotor blade. The crack started

at the mid-span inboard trim tab, ran chordwise to the spar, and turned

along the spar for about an inch. The crack originated from a hole in

the main rotor blade skin. Subsequent investigations revealed that the

manufacturing process utilized to drill the holes in the main rotor

blade skin can allow a fatigue crack to originate at these holes and

propagate in the skin. That condition, if not corrected, could result

in failure of a main rotor blade and subsequent loss of control of the

helicopter.

This AD supersedes AD 98-12-19, Amendment 39-10712 (63 FR 43299,

August 13, 1998), that required the same inspections as this AD.

However, since the issuance of that AD, it has been determined that

continued inspections are inadequate to ensure continued operational

safety and that mandatory terminating action is required to permanently

resolve this unsafe condition. Therefore, this AD mandates replacement

of all the affected main rotor blades prior to further flight after

November 15, 1998.

The FAA has reviewed RHC R44 Service Bulletin SB-27B, Revision B,

which recommends replacing daily preflight inspections with repetitive

inspections at intervals not to exceed 5 hours TIS and clarifies the

inspection procedure. The FAA has also reviewed RHC R44 Service

Bulletin SB-28, which describes procedures for main rotor blade

replacement and recommends replacement by December 31, 1998. Both

service bulletins are dated June 18, 1998.

RHC has also issued a Safety Alert to all Model R44 helicopter

owners, operators, and service centers which states that long term

usage of main rotor blades, part number (P/N) C016-1, is not

recommended. RHC recently commented to Rules Docket No. 98-SW-25-AD (AD

98-12-19). RHC states that AD 98-12-19 should not permit visual

inspections of main rotor blade, P/N C016-1, to continue indefinitely,

and requests that the compliance procedures be modified to require the

installation of redesigned main rotor blades, P/N C016-2, to ``avoid

possible catastrophic failure.'' The commenter also requests that NOTE

5 reference ``Revision B of R44 Service Bulletin 27'' for blade

inspection and ``R44 Service Bulletin 28'' for blade replacement. The

FAA concurs that as the TIS and total number of repetitive inspections

on these main rotor blades increase, so does the possibility for a

crack to develop and remain undetected. Based on that re-evaluation,

the FAA has determined that the required compliance time for main rotor

blade replacement should be earlier than the date stated in RHC R44

Service Bulletin SB-28 in order to ensure public safety.

Since an unsafe condition has been identified that is likely to

exist or develop on other RHC Model R44 helicopters of the same type

design, the FAA issued priority letter AD 98-22-16 to require

repetitively inspecting both holes on both the upper and lower surfaces

of each main rotor blade for cracks until the main rotor blades are

replaced with redesigned main rotor blades. The main rotor blades must

be replaced prior to further flight after November 15, 1998.

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 October 22, 1998 to all known U.S. owners and operators of

RHC Model R44 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 96 helicopters of U.S. registry will be

affected by this AD, that it will take approximately 2 work hours per

helicopter to perform the inspections and 10 work hours to replace both

main rotor blades on each helicopter, and the average labor rate is $60

per work hour. Required parts will cost approximately $3,900 per main

rotor blade. Based on these figures, the total cost impact of the AD on

U.S. operators is estimated to be $817,920, assuming one inspection and

replacement of both main rotor blades on all helicopters.

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 rule must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket No. 98-SW-56-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.

[[Page 62933]]

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. 106(g) 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing Amendment 39-10712 (63 FR

43299, August 13, 1998), and by adding a new airworthiness directive

(AD), Amendment 39-10874, to read as follows:

AD 98-22-16 Robinson Helicopter Company: Amendment 39-10874. Docket

No. 98-SW-56-AD. Supersedes AD 98-12-19, Amendment 39-10712, Docket

No. 98-SW-25-AD.

Applicability: Model R44 helicopters, serial numbers (S/N) 0002

through 0486, with main rotor blades, part number (P/N) C016-1,

installed, 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 (f) 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 a main rotor blade and subsequent loss of

control of the helicopter, accomplish the following:

(a) Within the next 5 hours time-in-service (TIS), perform a

dye-penetrant inspection of the main rotor blade skin around both

inboard trim tab alignment rivets as follows, referring to Figure 1.

BILLING CODE 4910-13-U

[[Page 62934]]

[GRAPHIC] [TIFF OMITTED] TR10NO98.000

BILLING CODE 4910-13-C

[[Page 62935]]

(1) Remove all paint around both rivets, exposing an area of

approximately 3/4'' in diameter, at the inboard trim tab on the top

and bottom of each main rotor blade (4 places per main rotor blade).

Use 180 grit or finer abrasive paper, followed by 600 grit or finer

paper to eliminate course sanding marks. Sand only in a spanwise

direction. Do not use chemical paint strippers.

(2) Inspect the main rotor blade skin around the rivets on the

upper and lower surfaces (4 locations) using a dye-penetrant

inspection method.

Note 2: Chordwise cracks in the paint up to 2 inches long which

are located along either inboard or outboard edge of the trim tab

are acceptable.

(b) Clean the sanded areas prepared in accordance with paragraph

(a) of this AD with 111-Trichloroethane or methyl ethyl ketone (MEK)

and then apply clear lacquer to seal the unpainted areas.

Note 3: Do not bend the inboard main rotor blade tabs from their

present position or utilize them for any subsequent main rotor blade

tracking adjustment.

(c) Thereafter, prior to the first flight of each day, or at

intervals not to exceed 5 hours TIS, whichever occurs first, using a

5-power or higher magnifying glass, visually inspect both upper and

lower main rotor blade skin surfaces around the inboard trim tab

rivets (4 locations) for cracks.

(d) If a crack is found, replace the main rotor blade with an

airworthy main rotor blade before further flight.

(e) Prior to further flight after November 15, 1998, install a

set of main rotor blades, main rotor blade P/N C016-2. This

constitutes terminating action for the inspections required by this

AD.

Note 4: Robinson Helicopter Company R44 Service Bulletin SB-27B,

Revision B, and Robinson Helicopter Company Service Bulletin SB-28,

both dated June 18, 1998, pertain to the subject of this AD.

(f) 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 5: 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.

(g) Special flight permits will not be issued.

(h) This amendment becomes effective on November 10, 1998, to

all persons except those persons to whom it was made immediately

effective by Priority Letter AD 98-22-16, issued October 22, 1998,

which contained the requirements of this amendment.

Issued in Fort Worth, Texas, on November 1, 1998.

Eric Bries,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.

[FR Doc. 98-30046 Filed 11-9-98; 8:45 am]

BILLING CODE 4910-13-U