[Federal Register Volume 66, Number 61 (Thursday, March 29, 2001)]
[Proposed Rules]
[Pages 17105-17115]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-7741]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-SW-13-AD]
RIN 2120-AA64


Airworthiness Directives; Bell Helicopter Textron, Inc. Model 
47B, 47B-3, 47D, 47D-1, 47G, 47G-2, 47G2A, 47G-2A-1, 47G-3, 47G-3B, 
47G-3B-1, 47G-3B-2, 47G-3B-2A, 47G-4, 47G-4A, 47G-5, 47G-5A, 47H-1, 
47J, 47J-2, 47J-2A, and 47K Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking.

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SUMMARY: This document proposes superseding an existing airworthiness 
directive (AD) for Bell Helicopter Textron, Inc. (BHTI) Model 47B, 47B-
3, 47D, 47D-1, 47G, 47G-2, 47G2A, 47G-2A-1, 47G-3, 47G-3B, 47G-3B-1, 
47G-3B-2, 47G-3B-2A, 47G-4, 47G-4A, 47G-5, 47G-5A, 47H-1, 47J, 47J-2, 
47J-2A, and 47K helicopters. That AD currently requires either 
recurring liquid penetrant or eddy current inspections of the main 
rotor blade grip (grip) threads for a crack. If a crack is detected, 
that AD requires, before further flight, replacing the cracked grip 
with an airworthy grip. That AD also establishes a retirement life of 
1200 hours time-in-service (TIS) for each grip. This AD contains the 
same requirements but adds two part numbers (P/N) to the applicability 
and requires only recurring eddy current inspections of the grip 
threads. This AD also requires reporting any results of the grip 
inspections to the FAA Rotorcraft Certification Office. This proposal 
is prompted by the results of an accident investigation, an operator 
survey conducted by a trade association, various comments concerning 
the current AD, and a further analysis of field service data. The 
actions specified by this AD are intended to prevent failure of a grip, 
loss of a main rotor blade, and subsequent loss of control of the 
helicopter.

DATES: Comments must be received on or before May 29, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 2001-SW-13-AD, 2601 Meacham Blvd., Room 
663, Fort Worth, Texas 76137. You may also send comments electronically 
to the Rules Docket at the following address: [email protected]. 
Comments may be inspected at the Office of the Regional Counsel between 
9 a.m. and 3 p.m. Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Marc Belhumeur, Aviation Safety 
Engineer, FAA, Rotorcraft Directorate, Rotorcraft Certification Office, 
Fort Worth, Texas 76193-0170, telephone (817) 222-5177, fax (817) 222-
5783.

SUPPLEMENTARY INFORMATION:   

Comments Invited

    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 before taking action on the proposed rule. The proposals 
contained in this document may be changed in light of the comments 
received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of this proposal. All 
comments submitted will be available in the Rules Docket for 
examination by interested persons. A report summarizing 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 mailed 
comments submitted in response to this proposal must submit a self-
addressed, stamped postcard on which the following statement is made: 
``Comments to Docket No. 2001-SW-13-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 Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 2001-SW-13-AD, 2601 Meacham Blvd., Room 
663, Fort Worth, Texas 76137.

Discussion

    On May 12, 1987, the FAA issued AD 86-06-08R1 (52 FR 24135, June 
29, 1987) that amended AD 86-06-08 (51 FR 11300, April 2, 1986). Those 
AD's required an initial and repetitive fluorescent dye penetrant 
inspection of each grip. On August 31, 2000, the FAA issued Emergency 
AD 2000-18-51 that superseded AD's 86-06-08 and 86-06-08R1. AD 2000-18-
51 requires initial and recurring liquid penetrent or eddy current 
inspections of the grip threads for a crack and, before further flight, 
replacing any cracked grip with an airworthy grip. That AD also 
establishes a retirement life of 1200 hours TIS for each grip.
    That action was prompted by the results of an investigation of an 
August 1998 accident in which a grip failed on a BHTI Model 47G-2 
helicopter due to a fatigue crack. An analysis of Australian field 
service data revealed fatigue cracks in the majority of the grips 
inspected. The requirements of that AD are intended to prevent failure 
of a grip, loss of a main rotor blade, and subsequent loss of control 
of the helicopter.
    Since issuance of Emergency AD 2000-18-51, other cracked grips with 
less than 1200 hours TIS have been discovered including one grip with a 
2-inch crack through the grip. Therefore, the FAA has determined that 
the liquid penetrent inspection is not adequate for finding cracks in 
the grip threads and proposes requiring eddy current procedures only. 
Because the eddy current procedure will find smaller cracks, the FAA 
proposes increasing the inspection interval from 200 hours TIS to 300 
hours TIS for each grip. In addition, two parts produced under Parts 
Manufacturer Approval (PMA) were omitted from the applicability section 
of the current AD but are added to this AD.

Disposition of Comments

    The FAA received additional data and comments about the current AD 
from 31 commenters, including the Experimental Aircraft Association 
(EAA), Helicopter Association International (HAI), and the National 
Agricultural Aviation Association (NAAA). We have reviewed each 
comment. Since many of the comments are similar, we will discuss each 
group of comments.
    A commenter states that AD 2000-18-51 should be rescinded because 
the extent of cracked grips in the United States fleet is not as 
extensive as the 70 percent of cracked grips found in the Australian 
survey. The FAA does not

[[Page 17106]]

concur with the request to rescind the AD. Although only 11 cracked 
grips have been found in the United States thus far, each of these 
grips is unairworthy and could result in a total fracture of the grip 
in flight. The FAA attributes the difference in the number of cracked 
grips found to be due to the unreliability of the dye penetrant 
inspection used by most U.S. operators versus the eddy current 
inspection used by the Australian operators. The FAA proposes that U.S 
operators only use eddy current inspections for finding cracks in the 
grip threads.
    Other commenters state that AD 2000-18-51 should be rescinded 
because the FAA Rotorcraft Directorate failed to apply United States 
BHTI Model 47 owner/operator user data to the equation when issuing the 
AD. The FAA does not concur. The FAA's Rotorcraft Directorate 
researched this safety concern before determining that an emergency AD 
was necessary. We continuously monitor in-service problems of the 
worldwide BHTI Model 47 fleet, taking into account accident data and 
service difficulty information from the entire fleet. The FAA received 
data, most recently from Australia and Canada, indicating that BHTI 
Model 47 grips were cracking. We asked BHTI to submit all the field 
service information they had on the BHTI Model 47 grips. The 
airworthiness authorities in Australia and Canada had also extensively 
researched and analyzed the grip problem. Using this information, the 
FAA determined that fatigue cracks in the grips are likely to exist on 
the BHTI Model 47 helicopters. This condition, if not corrected, could 
result in failure of a grip, loss of a main rotor blade, and subsequent 
loss of control of the helicopter.
    Several commenters also state that the United States user data will 
show that there has not been one accident, incident, or other 
maintenance issue concerning the BHTI Model 47 blade grip in over 40 
years. The FAA does not concur. The United States data actually shows 
two accidents in the United States because of fatigue cracking in the 
grip threads. One resulted in a fatality in New Jersey during 1971 and 
the other involved injuries in Iowa during 1972. The United States data 
also shows 11 grips with cracks and 5 of those had less than 1200 hours 
TIS. An EAA survey shows that one operator found a 2-inch crack through 
the threads of his grip as a result of complying with AD 2000-18-51.
    A commenter also states that AD 2000-18-51 should be rescinded 
because the basis for the AD was a Bell 47 accident that occurred in 
Canada on August 13, 1998. That commenter states that neither the 
accident investigation report, Transportation Board of Canada (TSB) 
Report No. A98O0214, the accident, nor the resulting Transport Canada 
AD called for the extreme measures the FAA took when it issued the 
AD's. Other commenters offer similar comments. The FAA does not concur. 
The TSB suggested in Report No. A98O0214 under ``Safety Action'' the 
possible need for a fatigue crack examination at an interval that 
provides a greater margin of safety than the existing inspection cycle. 
Transport Canada changed the initial inspection from 1200 hours to 600 
hours TIS and thereafter at intervals not to exceed 300 hours TIS.
    Without providing substantiating data, many commenters state that 
AD 2000-18-51 should be rescinded because they think the history on the 
helicopter that crashed August 13, 1998, in Canada is questionable. The 
FAA does not concur because the records indicate that the helicopter 
was certified, equipped, and maintained in accordance with existing 
regulations and approved procedures.
    Some commenters state that the AD should differentiate between the 
grips. They state that it was one of the smaller grips, P/N 47-120-135-
5, that was involved in the 1998 Canadian accident and that the larger 
grips were only involved in one accident and that grip had over 5600 
TIS when it fractured. The FAA does not concur because 41 of the larger 
grips were found with cracks. Based on this service history, we have 
determined that both smaller and larger grips require the same 
inspection interval.
    Some commenters state that the inspection intervals should be 
increased to 300 hours TIS similar to the previous United States AD and 
to the current Canadian AD to allow operators more operational use 
between inspections. The FAA partially concurs. The Canadian AD only 
allows eddy current inspections. The FAA believes liquid penetrant 
inspections may not be effective in detecting a small crack. Therefore, 
we propose to require the use of eddy current inspection exclusively. 
Similarly, because we now believe that it is unlikely that a crack will 
propagate to failure within 300 hours TIS for either the smaller or 
larger grip, we propose to increase the inspection intervals for eddy 
current inspections from 200 hours TIS to 300 hours TIS.
    Commenters state that the AD should be rescinded and allow AD 86-
06-08R1 to be effective because that AD has adequately eliminated the 
unsafe fatigue cracking condition. The FAA does not concur because AD 
86-06-08-R1 does not address the cracking found in grips with less than 
1200 hours TIS.
    Other commenters state that during recurring inspections, the 
reinstallation of the steel adapter nuts to the aluminum grip would 
damage the aluminum grip and create an unsafe condition. The FAA does 
not concur. Both the adapter and the grip must be cleaned and inspected 
for any burrs, damage, or out-of-tolerance threads. These grips have 
had recurring inspections since 1985, and the service history suggests 
that reinstalling the adapter to the grip threads produces no damage if 
done properly. Plus, we are extending the TIS intervals for inspecting 
the grips.
    A commenter states that the AD should be rescinded because 36 of 
the grips identified in the field survey were P/N 47-120-252-3, and 
these grips only have a 300-hour retirement life. They believe that 
cracks found on these grips should not be considered since the grips 
should have been retired at 300 hours TIS. The data the FAA reviewed 
does not support that supposition, and we do not concur. The grip, P/N 
47-120-252-3, is identical to the grips, P/N 47-120-252-7 and 47-120-
252-11, except the grip, P/N 47-120-252-3, does not have bushings 
installed. The threaded area of these grips is identical to the 
threaded area on grips, P/N 47-120-252-7 and 47-120-252-11; therefore, 
a crack found in the threads of a grip, P/N 47-120-252-3, is relevant 
to the FAA's analysis.
    A commenter states that the AD should be rescinded because the 
reason the grip fractured in Canada during 1998 was due to water lodged 
in the grip's thread and pitting in the roots of the threads. The FAA 
does not concur. The accident report stated water was dislodged during 
disassembly of the grip from the hub. This does not mean that water was 
in the threads, and the report does not suggest water in the threads. 
The report states there was extensive pitting in the threads. These 
pits were 0.0008 inch or less and cannot be seen with the naked eye. 
This kind of micro pitting is allowed by military specifications and 
manufacturing procedures. The FAA believes that the main reason the 
fatigue cracks have started in the root of the threads is because the 
root radii are not controlled and have been shown to be as sharp as 
0.001 inch.
    Numerous commenters state that the AD should be rescinded because 
the economic impact was underestimated and did not address that 
replacement parts were unavailable. The commenters also state that this 
AD created an unnecessary financial hardship on

[[Page 17107]]

operators, possibly forcing numerous operators out of business. The FAA 
understands these concerns. Several operators comment that the average 
economic impact per BHTI Model 47 helicopter ranged from $8,000 to 
$32,000. Their economic impact cost may be indicative of most costs 
associated with a business having to comply with the AD. However, 
normally AD cost calculations do not go beyond initial labor and parts 
costs and do not include costs that operators may incur in individual 
maintenance or cost that operators might pass on to others. The FAA 
recognizes that there are additional costs associated with a shorter 
retirement life on these rotorcraft. Assuming the helicopter is 
operated for 300 hours TIS per year, the cost of replacing the grips at 
1200 hours vs. 5000 hours and changing the inspection requirements is 
calculated as follows:

Additional part replacement cost:
    ((300hr/yr)/(5000hr))((2ea/set)($4000))=$480 per 300hr TIS year for 
original set.
    ((300hr/yr)/(1200hr))((2ea/set)($4000))=$2000 per 300hr TIS year 
for reduced life set.
    $2000-$480=$1520 per 300hr TIS year per set replacement.
    Additional inspections and installations (job) cost:
    ((300hr/yr)/(5000hr)) (10hr/job)($60 per 
hr)((1job(initial)+(5000hr-1200hr)/(300hr/job))=$504 per 300hr TIS 
year.
    ((300hr/yr)/(1200hr))(10hr/job)($60 per 
hr)((1job(initial)+(1200hr)/(200hr/job))=$1050 per 300hr TIS year.
    $1050-$504=$546 per 300hr TIS year.

    Total additional cost per 300hr TIS yr $1520+$546=$2066 per 300hr 
TIS year.
    Total additional cost per hr TIS is $2066/300hr TIS=$7 per hr TIS.
    These additional costs do not include the economic impact to the 
operator if the parts are not available. The FAA recognizes that if 
parts are not available, an operator's helicopter may become grounded 
and result in an overwhelming financial burden on the operator. When 
adopting a regulation, the FAA must determine that the benefits of the 
intended regulation justify the cost. The FAA did not anticipate that a 
significant shortage of parts existed and the subsequent grounding of a 
portion of the fleet. Even though the FAA did not anticipate the 
shortage, despite the shortage of parts, we would still have issued the 
AD based on the extent of the unsafe condition. The AD was intended to 
restore the level of safety established in the certification basis and 
the type design. If this part failed, the result could be catastrophic. 
For example, one operator reported finding a 2-inch crack in a grip as 
a result of the current AD.
    One commenter states that the AD should be rescinded because the 
manufacturer stated that the AD is unwarranted. The FAA does not agree. 
There has been enough data reviewed that shows cracks have occurred 
prior to the 1200-hour life limit. The FAA does not allow flight with a 
crack in a critical component. Cracks do develop at less than 1200 
hours TIS, and neither the initiation mechanism nor the crack growth 
characteristics have been determined; therefore, the recurring 
inspection mitigates risk. The FAA is also concerned that without 
design changes, newly produced parts could also develop cracks before 
the manufacturer's recommended 1200-hour life limit. The manufacturer 
has agreed to a crack propagation test on one of the existing grips, P/
N 47-120-135-5, which had cracks show up during an eddy current 
inspection. The manufacturer has also agreed to redesign the grip to at 
least include a change to MIL-S-8879 threads with controlled root 
radius.
    Several commenters state that the AD should not have gone out as an 
Emergency AD because the Rotorcraft Directorate did not follow the risk 
assessment process in the Small Airplane Directorate's ``Airworthiness 
Concerns Process Guide'' (guide). The FAA agrees that we did not follow 
the risk assessment process in that guide because that process was 
originally developed to address small airplanes under a type 
certificate whose owner no longer provides engineering support for the 
type certificate. Since that guide as it currently exists may not be 
appropriate for rotorcraft, we do plan to evaluate a procedure that 
could be used for rotorcraft. The FAA decided to issue the Emergency AD 
because of an in-flight failure of a grip at approximately 200 hours 
TIS.
    We have identified an unsafe condition that is likely to exist or 
develop on other BHTI Model 47B, 47B-3, 47D, 47D-1, 47G, 47G-2, 47G2A, 
47G-2A-1, 47G-3, 47G-3B, 47G-3B-1, 47G-3B-2, 47G-3B-2A, 47G-4, 47G-4A, 
47G-5, 47G-5A, 47H-1, 47J, 47J-2, 47J-2A, and 47K helicopters of the 
same type designs. The proposed AD would supersede AD 2000-18-51 with 
the following requirements:
     For grips, P/N 47-120-135-2, 47-120-135-3, 47-120-135-5, 
47-120-252-1, 47-120-252-7, 47-120-252-11, and for grips manufactured 
under PMA, P/N 74-120-252-11, 74-120-135-5, R74-120-252-11, and R74-
120-135-5, conduct eddy current inspections of the threads of both 
grips as follows:
     Within 300 hours TIS since initial installation on any 
helicopter or within 10 hours TIS for grips with 300 or more hours TIS, 
or within 200 hours TIS since last liquid penetrant or eddy current 
inspection, whichever comes first, conduct an eddy current inspection 
in accordance with Appendix 1 or an equivalent FAA-approved procedure 
that contains the requirements of the procedure in Appendix 1. 
Thereafter, conduct the eddy current inspection at intervals not to 
exceed 300 hours TIS.
     Report the results of each inspection to the FAA 
Rotorcraft Certification Office by providing the information requested 
in the sample format report in Appendix 3. Reporting requirements have 
been approved by the Office of Management and Budget and assigned OMB 
control number 2120-0056.
     Before further flight, replace any cracked grip with an 
airworthy grip.
    The proposed AD would require maintaining the current retirement 
life of 1200 hours TIS for each affected grip.
    The FAA estimates that 1130 helicopters of U.S. registry will be 
affected by this AD, that it will take approximately 10 work hours per 
helicopter to accomplish the disassembly, inspection, and reassembly of 
the grips from the helicopter, and that the average labor rate is $60 
per work hour. Required parts, if a grip needs to be replaced, will 
cost approximately $4,000 per grip (there are two grips on each 
helicopter). Based on these figures, the total cost impact of the AD on 
U.S. operators is estimated to be $9,718,000, assuming one inspection 
per helicopter and replacement of both grips on each helicopter.
    The regulations adopted herein will not have a substantial direct 
effect 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, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    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

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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 U.S.C. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing Amendment 39-11983 and by 
adding a new airworthiness directive to read as follows:

Bell Helicopter Textron, Inc.: Docket No. 2001-SW-13-AD. Supersedes 
AD 2000-18-51, Amendment 39-11983, Docket No. 2000-SW-35-AD.

    Applicability: Model 47B, 47B-3, 47D, 47D-1, 47G, 47G-2, 47G2A, 
47G-2A-1, 47G-3, 47G-3B, 47G-3B-1, 47G-3B-2, 47G-3B-2A, 47G-4, 47G-
4A, 47G-5, 47G-5A, 47H-1, 47J, 47J-2, 47J-2A, and 47K helicopters, 
with main rotor blade grips, part number (P/N) 47-120-135-2, 47-120-
135-3, 47-120-135-5, 47-120-252-1, 47-120-252-7, 47-120-252-11, 74-
120-252-11, 74-120-135-5, R74-120-252-11, and R74-120-135-5, 
installed, certified in any category.

    Note 1: This AD applies to each helicopter identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise 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 request approval for an 
alternative method of compliance in accordance with paragraph (e) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of a main rotor blade grip (grip), separation 
of a main rotor blade, and subsequent loss of control of the 
helicopter, accomplish the following:
    (a) Conduct an eddy current inspection of the threads of both 
grips for a crack in accordance with Appendix 1 of this AD or an 
equivalent FAA-approved procedure containing the requirements of the 
procedure in Appendix 1 within 300 hours time-in-service (TIS) since 
initial installation on any helicopter or within 10 hours TIS for 
grips with 300 or more hours TIS or within 200 hours TIS since the 
last liquid penetrant or eddy current inspection of grip threads, 
whichever comes first.
    (1) Thereafter, conduct the eddy current inspection in 
accordance with Appendix 1 of the AD or an equivalent FAA-approved 
procedure containing the requirements of the procedure in Appendix 1 
at intervals not to exceed 300 hours TIS.
    (2) Report the results of each inspection to the FAA Rotorcraft 
Certification Office within 7 calendar days. Reporting requirements 
have been approved by the Office of Management and Budget and 
assigned OMB control number 2120-0056.

    Note 2: See Appendix 2 of this AD for a list of known eddy 
current inspection facilities.

    (b) If a crack is detected, before further flight, replace any 
cracked grip with an airworthy grip.
    (c) On or before 1200 hours TIS, replace each grip with an 
airworthy grip.
    (d) This AD establishes a retirement life of 1200 hours TIS for 
the grips, P/N 47-120-135-2, 47-120-135-3, 47-120-135-5, 47-120-252-
1, 47-120-252-7, 47-120-252-11, 74-120-252-11, 74-120-135-5, R74-
120-252-11, and R74-120-135-5.
    (e) 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, Rotorcraft 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, Rotorcraft Certification Office.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Rotorcraft Certification Office.

    (f) Special flight permits may be issued in accordance with 14 
CFR 21.197 and 21.199 to operate the helicopter to a location where 
the requirements of this AD can be accomplished.

Appendix 1--Nondestructive Inspection Procedure

Task: Eddy Current (ET) Inspection of Mast Threads for Cracks

1.0  AREA OF INSPECTION

    1.1 The inboard inside diameter machined threads (reference 
figure 1).

2.0   EQUIPMENT

    2.1 Zetec Miz-20/22, Phasec 2200 or equivalent piece of 
equipment.
    2.2  Match molded ET probe SPC-193 (100kHz) or equivalent. (See 
Figure 3.)
    2.3  Reference standard EC-010-021, or equivalent. (See Figures 
4 and 5.)
    2.4  Light oil.

3.0  PERSONNEL REQUIREMENTS

    3.1  Personnel performing the ET inspection must be minimally 
qualified to a Level II in ET inspection, certified in accordance 
with an industry accepted standard (such as, ATA-105, NAS-410, or 
MIL-STD-410) or an FAA accepted company procedure.

4.0  STANDARDIZATION

    4.1  Connect probe to flaw detector and turn power on.
    4.2  Adjust the Phasec 2000 as shown in table 1. Adjust all 
other equipment as necessary.
    4.3  Adjust the V:H gain ratio to 1.5:1--2:1.
    4.4  Monitor the crack response when moving the probe in one 
direction only across each EDM notch of the standard. Adjust the 
coarse gain for a crack response of 2-3 units from the smallest 
(0.04") notch. Record the number units of displacement and noise 
level for each of the EDM notches.

5.0  PRE INSPECTION

    5.1  The part shall be clean and free of loose debris.
    5.2  A thin coating of clean oil may be applied to the teeth to 
help the ET probe slide easily.

6.0  INSPECTION

    6.1  Place the probe into the threaded area and slide it in the 
same direction as was done on the standard while monitoring the 
screen for root cracks. Moving the probe in the same direction 
produces a repeatable display that allows for more accurate flaw 
size determination. Scan the probe along each individual thread 
until all the threads are inspected. (See Figures 2 and 3.)

7.0  EVALUATION

    7.1  Repeat standardization and rescan any areas where there is 
a vertical crack-like deflection.
    7.2  If indication persists, mark the location on the part. 
Record the number units of displacement, phase orientation, and 
noise level.

8.0  ACCEPT/REJECT CRITERIA

    8.1  All repeatable crack-like indications above the noise level 
detected shall be cause for rejection.
BILLING CODE 4910-13-U

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BILLING CODE 4910-13-C

Appendix 2--Partial List of Nondestructive Inspection Testing 
Facilities Identified by Operators and FAA

Met Chem Testing Laboratories Inc., 369 W. Gregson Ave. (3085 S.), 
Salt Lake City, Utah 84115-3440, Phone: (801) 487-0801, FAX: (801) 
466-8790 www.metchemtesting.com
Galactic NDT Services, 10728 D. South Pipeline RD, Hurst, Texas 
76053, Phone: (800) 458-6387.
Global Testing Technologies, 1173 North Service Rd. Unit D3, 
Oakville Toronto Canada, Phone: (905) 847-9300, FAX: (905) 847-9330.
Paragon Services, Inc., 1015 S. West St., Wichita, KS 67213, Phone: 
(316) 945-5285, FAX: (316) 945-0629.
NOE Services, 8775 E. Orchard Rd., #809, Englewood, CO, Phone: (303) 
741-0518, FAX: (303) 741-0519.
Applied Technical Services, Inc., 1190 Atlanta Industrial Drive, 
Marietta, GA 30066, Phone: (770) 423-1400, FAX: (770) 514-3299.
Rotorcraft Support, Van Nuys CA 91406, Phone: (818) 997-7667, FAX: 
(818) 997-1513.
    Other FAA Approved repair facilities may be used.

[[Page 17115]]

Appendix 3--AD Compliance Inspection Report (Sample Format), Bell Model 
47 Main Rotor Blade Grip

    Provide the following information and mail or fax it to: 
Manager, Rotorcraft Certification Office, Federal Aviation 
Administration, Fort Worth, Texas, 76193-0170, USA, Fax: 817-222-
5783.
Aircraft Registration No:----------------------------------------------
Helicopter Model:------------------------------------------------------
Helicopter Serial Number:----------------------------------------------
Owner and Operator of the Helicopter:----------------------------------

------------------------------------------------------------------------
                                                     Grip #1    Grip #2
------------------------------------------------------------------------
Part Number:
Serial Number:
Hours TIS on the part at Inspection:
Crack Found (Y/N) (If yes, describe below.)
------------------------------------------------------------------------

Description of Findings

Who performed the inspections?-----------------------------------------
If a crack was found, describe the crack size, location, and 
orientation (provide a sketch or pictures with the grip part and serial 
number).---------------------------------------------------------------
Provide any other comments.--------------------------------------------

    Issued in Fort Worth, Texas, on March 23, 2001.
Mark R. Schilling,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.

[FR Doc. 01-7741 Filed 3-28-01; 8:45 am]
BILLING CODE 4910-13-U