AD 2001-17-17

[Federal Register Volume 66, Number 168 (Wednesday, August 29, 2001)]
[Rules and Regulations]
[Pages 45584-45594]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 01-21749]



[[Page 45584]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-SW-13-AD; Amendment 39-12408; AD 2001-17-17]
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: Final rule.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD) that applies to 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 as the existing AD 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 AD 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.

EFFECTIVE DATE: October 3, 2001.

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:

Background Information

    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 penetrant or eddy current 
inspections of the grip threads for a crack and, before further flight, 
replacing any cracked grip with an airworthy grip. That Emergency AD 
also establishes a retirement life of 1200 hours TIS for each grip. 
That Emergency AD was published in the Federal Register on November 15, 
2000 (65 FR 68884) as a final rule, request for comments.
    Airworthiness Directive 2000-18-51 was prompted by the results of 
an investigation of an August 1998 Canadian accident in which a grip 
failed on a BHTI Model 47G-2 helicopter due to a fatigue crack. An 
analysis of 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 issuing 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. Since then, the FAA has also determined that 
the liquid penetrant inspection is inadequate for finding smaller 
cracks in the grip threads. Additionally, two parts produced under a 
Parts Manufacturer Approval (PMA), P/Ns R74-120-252-11 and R74-120-135-
5, were inadvertently omitted from the applicability of AD 2000-18-51. 
Based on these findings, the earlier accident investigation, a further 
analysis of field service data, the results of an operator survey 
conducted by a trade association, and several comments received as a 
result of the issuance of AD 2000-18-51 as a final rule, request for 
comments, the FAA issued a Notice of Proposed Rulemaking (NPRM) on 
March 23, 2001 (66 FR 17105, March 29, 2001) proposing to supersede AD 
2000-18-51.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the numerous comments received from the 17 commenters. The comments and 
the FAA's responses are listed in the following table:

------------------------------------------------------------------------
                Comment                            FAA response
------------------------------------------------------------------------
1. A couple of commenters state that     The FAA concurs and will place
 the FAA should make available to the     in the public docket
 public all of the history related to     anyinformation that is not
 the failed grips, to include the         proprietary. Anyone wishing
 damage history, manufacture date, and    this information can obtain it
 hours.                                   by submitting a request under
                                          the Freedom of Information Act
                                          to the office provided under
                                          the caption FOR FURTHER
                                          INFORMATION CONTACT.
2. Several commenters state that the     The FAA does not concur. The
 grips should be eddy current inspected   FAA has determined that the
 before initial installation to ensure    300-hour TIS inspection
 that they are airworthy.                 interval is sufficient to
                                          ensure safety.
3. Several commenters question the       The FAA does not concur. The
 accuracy of the information gathered     grip in question was within
 from the Canadian accident. Many         specifications, and records
 commenters state that the 1998           indicate that the helicopter
 accident seems to be a result of poor    on which the grip was
 quality control. Several other           installed was certified,
 commenters state that the grip had a     equipped, and maintained in
 questionable history or incomplete       accordance with acceptable
 records.                                 procedures.
4. A few commenters state that the FAA   The FAA does not concur. The
 has not shown that the affected grips    FAA believes that a crack will
 are unsafe after 1200 hours TIS. The     not propagate to failure
 commenters state that if the FAA         within 300 hours TIS only if
 believes a crack will not propagate to   the part life is limited to
 failure within 300 hours TIS for         1200 hours TIS. After 1200
 either the smaller or larger grip, the   hours TIS, the probability of
 grip retirement life should remain at    cracking is too high and
 the original 2500 hours for wood-blade   recurring inspections may not
 grips and 5000 hours for metal-blade     provide an adequate level of
 grips.                                   safety. Also, recurring
                                          inspections by themselves are
                                          not a terminating action.

[[Page 45585]]

 
5. A couple of commenters state that it  The FAA does not concur. The
 is not clear who is responsible for      owners/operators are
 reporting results of the grip eddy       responsible for complying with
 current inspection to the FAA. The       the AD, including reporting
 commenters state that the                the results of the grip eddy
 nondestructive inspection (NDI)          current inspections to the
 facility should be responsible for       FAA. Furthermore, the NDI
 reporting the results.                   facility typically only
                                          receives minimal aircraft
                                          information when parts are
                                          sent to them for inspection;
                                          therefore, if they were
                                          required to report to the FAA
                                          they would need to do an
                                          inquiry to obtain all the FAA-
                                          requested information.
6. Two commenters state that the public  The FAA partially concurs.
 should be kept abreast of the on-going   Detailed test results are
 BHTI blade grip propagation tests. The   generally proprietary to the
 commenters also state that if the        manufacturer; however, if the
 tests show that a crack will not         BHTI blade grip propagation
 propagate to failure within 300, 400,    tests justify a change to the
 500, or 600 hours TIS, the FAA should    eddy current inspection
 change the eddy current inspections to   intervals, the FAA will adjust
 match the BHTI test results.             the intervals as appropriate.
7. Several commenters state that         The FAA does not concur. Even
 previous grip failures may have been     though these types of abuses
 initiated by sudden stoppage, trailer    could damage the grips, there
 transporting, rotor over-speed, bad      has been no clear connection
 installation procedures, poor            between these types of abuses
 maintenance, or other misuse.            and all the cracked grips.
8. One commenter states that all new     The FAA does not concur; it has
 blade grips with redesigned root radii   no data to support
 may still have cracking problems, and    recommending a voluntary eddy
 the FAA should issue a Special           current inspection of the
 Airworthiness Information Bulletin       redesigned grips.
 (SAIB) to that effect and recommend a
 voluntary eddy current inspection at
 300-hour TIS intervals.
9. Two commenters state that the FAA     The FAA does not concur. Only
 should send notification of proposed     emergency ADs are sent to each
 AD action to each registered owner and   registered owner followed by
 not just post a notice in the Federal    the publication of the final
 Register.                                rule in the Federal Register.
                                          In compliance with the
                                          Administrative Procedures Act,
                                          notification of proposed
                                          action is given by Federal
                                          Register notice. However,
                                          these published notices may be
                                          accessed via the Internet.
10. One commenter states that the        The FAA does not concur. Both
 reinstallation of the steel adapter      the adapter and the grip
 nuts to the aluminum grip during         should be cleaned and
 recurring inspections can create an      inspected for any burrs,
 unsafe condition. Another commenter      damage, or out-of tolerance
 states that frequent dismantling of      threads before any
 these components is harmful.             reinstallation. These grips
                                          have had recurring inspections
                                          since 1985, and the service
                                          history suggests that
                                          reinstalling the adapter to
                                          the grip threads causes no
                                          damage if done properly.
11. A few commenters state that an x-    The FAA does not concur. There
 ray would be better than an eddy         is no data that suggests that
 current inspection for finding cracks    x-rays would increase the
 in the grip threads.                     likelihood of finding cracks
                                          in the grip threads. Compared
                                          to eddy current inspections, x-
                                          ray inspections are more
                                          expensive and do not offer any
                                          advantage other than finding
                                          internal flaws. Internal flaws
                                          are not a concern in grip-
                                          thread cracking. The grips
                                          cylindrical design also makes
                                          the x-ray inspection difficult
                                          to perform.
12. Many commenters state that the FAA   The FAA does not concur. The
 does not know what caused the problems   FAA has extensively researched
 with the grips, does not have            this safety concern and is
 sufficient or reliable data, and has     continuously monitoring in-
 based ADs on faulty equipment and        service problems of the fleet
 questionable airworthiness records.      worldwide, taking into account
                                          accident data and service
                                          difficulty information. The
                                          most common reason for
                                          cracking has been high stress
                                          concentrations in the affected
                                          parts. All of the cracked
                                          grips had a high stress
                                          concentration due to the sharp
                                          radii in the thread root.
13. One commenter states that there      The FAA does not concur.
 have been no instances in the U.S.       Neither AD 86-06-08 nor AD 86-
 fleet where the old 300-hour zyglo       06-08 R1 addressed the
 inspection has not maintained an         cracking found in grips with
 adequate level of safety; therefore,     less than 1200 hours TIS.
 AD 86-06-08 adequately prevents an       Also, the FAA has received
 unsafe condition.                        reports outlining situations
                                          where zyglo inspections have
                                          not found known cracks.
14. Two commenters state that a 300-     The FAA concurs and has made
 hour TIS inspection interval should be   that change in this final
 allowed if the last inspection           rule.
 performed on the grips was an eddy
 current inspection.
15. Many commenters state that the FAA   The FAA concurs and has made
 should change the requirement of the     that change in this final rule
 initial inspection from ``the initial    AD.
 inspection is within 10 hours TIS for
 grips that have 300 hours or more
 hours TIS'' to ``an initial inspection
 that is within 10 hours TIS for grips
 that have not had any previous
 inspection and have 300 hours or more
 TIS''.
16. A commenter states that 8 days and   The FAA does not concur.
 revenue of $5,000 a day should be        Although the FAA understands
 added to the economic impact of the AD.  that some operators could have
                                          their helicopters grounded for
                                          several days, which will
                                          result in a loss of revenue,
                                          any cost estimate based on
                                          assumed ground time and lost
                                          revenue would be speculative.
                                          The FAA bases its economic
                                          impact costs only on known
                                          parameters such as labor and
                                          parts costs.
17. A commenter states that until        The FAA does not concur. Data
 everyone agrees on correct procedures,   has shown that cracks can
 only a one-time inspection should be     develop any time during a
 required.                                grip's service life, and
                                          inspecting the grips on a
                                          regular basis is needed to
                                          prevent a failure.
18. A couple of commenters point out     The FAA partially concurs.
 that the Canadian and Australian         Transport Canada and the
 airworthiness authorities have           Civilian Aviation Safety
 retained the original retirement lives   Authority of Australia have
 of the grips and have not amended        changed the initial eddy
 their current ADs, and according to a    current inspection from 1200
 recent survey, the majority of the       hours TIS to 600 hours TIS.
 grips in Canada reach their retirement   Neither authority has changed
 life with no defects.                    the grip's retirement life;
                                          however, they have their own
                                          rules and procedures and must
                                          make their own safety
                                          determinations.

[[Page 45586]]

 
19. One commenter states that the        The FAA does not concur. The
 proposed AD should not be issued. The    accident report states that
 commenter explains his belief that the   water was dislodged during
 grip installed on the 1998 Canadian      disassembly of the grip from
 accident fractured because water was     the hub. This does not mean
 lodged in the grip's thread and          that water was in the threads,
 because pitting was in the thread        nor does the report suggest
 roots.                                   water in the threads. The
                                          report states that there was
                                          extensive pitting in the
                                          threads. The pits are 0.0008
                                          inch or less and cannot be
                                          seen by the naked eye.
20. One commenter states that the 1971   The FAA does not concur. The
 and 1972 accidents that occurred in      grips involved in those
 the U.S. were a result of installing     accidents were P/N 47-120-135-
 the wrong grips.                         1 and -2. Those grips were
                                          approved for the BHTI Model 47
                                          G-2 helicopters. The newer
                                          approved grips are P/N 47-120-
                                          135-3. There are no
                                          differences between either of
                                          these part-numbered grips at
                                          the threads.
21. Several commenters state that the    The FAA does not concur. The
 problem with the failed/fractured        FAA has not found any
 grips is a manufacturing defect or a     manufacturing defect or
 quality control problem. Many            quality control problem.
 commenters believe that the
 manufacturer should inspect each grip
 before it is sold and that the same
 requirement should be placed on grips
 manufactured under PMA.
22. One commenter states that an eddy    The FAA does not concur.
 current inspection of the grip, before   Although this type of abuse
 further flight, should be added to the   could damage grips, there has
 AD in the event of a sudden stoppage     been no documented connection
 occurrence. Also, as part of the         between sudden stoppage and
 reporting the requirements, add the      the cracked grips. Also, all
 question ``Has this grip had any prior   sudden stoppages require
 history involving a sudden stoppage      removal and disassembly of the
 incident or aircraft accident (sudden    main rotor. If blade impact is
 stoppage as defined in the Bell 47       violent, or if the drag brace
 Maintenance and Overhaul                 belt is sheared and the aft
 Instructions)?''.                        side of the blade butt
                                          contacts the aft outboard side
                                          of the grip, the complete hub
                                          assembly must be replaced.
23. One commenter states that the        The FAA does not concur. The
 assumption that dye penetrant            FAA has received reports of
 inspections are not reliable cannot be   confirmed cracks missed by a
 accepted. The commenter also states      dye penetrant inspection and
 that two labs, one of which is listed    found by an eddy current
 in Appendix 2 of the proposal as a       inspection. Although dye
 recommended facility, state that, for    penetrant inspections remain a
 the purpose of the proposed              reliable inspection method,
 inspection, ``the high sensitivity       the FAA has determined that
 level of the dye penetrant method        the eddy current inspection is
 would be just as accurate as the eddy    more appropriate when
 current method.'' Additionally, the      inspecting for cracks in the
 commenter states that United States      blade grip threads.
 has been using a dye penetrant
 inspection method, probably testing
 more aircraft with more hours than
 other countries, inspection. and we
 have had no accidents''.
24. One commenter states that few of     The FAA does not concur.
 the facilities identified in Appendix    Paragraph (e) of the NPRM and
 2 of the proposal can perform the        paragraph (g) of this AD
 proposed tests because they do not       address the procedure for
 have the probe required to do so. This   obtaining an alternative
 situation can cause a hardship on        method of compliance (AMOC).
 operators who are on tight schedules     Appendix 2 contains only a
 or live in remote areas. The commenter   partial list of known eddy
 states that there is no mention in the   current inspection facilities.
 proposal of any alternate means of       If any of these facilities do
 compliance when rapid inspection         not have the equipment or
 services or parts are not available.     expertise to inspect the
                                          threads, then another facility
                                          will need to be found or an
                                          AMOC that provides an
                                          acceptable level of safety
                                          must be requested and approved
                                          by the Manager, Rotorcraft
                                          Certification Office.
25. Several commenters state that the    The FAA does not concur.
 inspection should be performed during    Inspection intervals of 600
 the normally scheduled 600 and 1200-     and 1200 hours TIS do not
 hour inspections.                        provide an adequate level of
                                          safety based on the service
                                          history of these grips.
26. One commenter states that the        The FAA does not concur. The
 manufacturer changed thread standards    FAA has determined that there
 in the late 1970's. The commenter        was no physical change to the
 believes that is when the problem        thread standards or design in
 supposedly started and AD 86-06-08 was   that timeframe.
 issued.
27. One commenter asks why we don't      The FAA does not concur. There
 state the fact that all 4 grip           is no data showing that sudden
 failures occurred on rotor systems       stoppage is connected to grip
 that had suffered sudden stoppage.       failures and the commenter did
                                          not provide any information
                                          showing that all 4 grip
                                          failures suffered sudden
                                          stoppage or that sudden
                                          stoppage contributed to the
                                          failures.
------------------------------------------------------------------------

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes described 
previously in the disposition of comments 14 and 15. Additionally, the 
FAA discovered an error in two of the P/Ns given in paragraph (d) of 
the NPRM; those P/Ns are corrected in this final rule. For better 
clarity, the FAA has also reorganized the compliance times for 
performing the eddy current inspections and has added an NDI testing 
facility to Appendix 2. The FAA has determined that these changes will 
neither increase the economic burden on any operator nor increase the 
scope of the AD.
    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 re-assembly 
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 action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44

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FR 11034, February 26, 1979); and (3) 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 final 
evaluation has been prepared for this action and it is contained in the 
Rules Docket. A copy of it may be obtained from the Rules Docket at the 
FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham 
Blvd., Room 663, Fort Worth, Texas.

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 39-11983 (65 FR 
68884, November 15, 2000), and by adding a new airworthiness directive 
(AD), Amendment 39-12408, to read as follows:

2001-17-17  Bell Helicopter Textron, Inc.: Amendment 39-12408. 
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, R47-120-252-11, and R47-120-135-5, 
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 
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 (g) 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:
    (1) Within 300 hours time-in-service (TIS) since initial 
installation on any helicopter for a grip with less than 300 total 
hours TIS;
    (2) Within 10 hours TIS for a grip with 300 or more total hours 
TIS that has not had any previous dye penetrant or eddy current 
inspection;
    (3) Within 200 hours TIS since the last dye penetrant 
inspection; OR
    (4) Within 300 hours TIS since the last eddy current inspection, 
whichever occurs first.
    (b) Thereafter, conduct the eddy current inspection in 
accordance with Appendix 1 of this AD or an equivalent FAA-approved 
procedure containing the requirements of the procedure in Appendix 1 
at intervals not to exceed 300 hours TIS.
    (c) 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.

    (d) If a crack is detected, before further flight, replace any 
cracked grip with an airworthy grip.
    (e) On or before 1200 hours TIS, replace each grip with an 
airworthy grip.
    (f) 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, R47-
120-252-11, and R47-120-135-5.
    (g) 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.

    (h) 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.
    (i) This amendment becomes effective on October 3, 2001.

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.

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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
<a href="http://www.metchemtesting.com">www.metchemtesting.com</a>

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

Palm Beach Aircraft Propeller, Inc
Palm Beach County Park Airport
2633 Lantana Road
Suite 23, Bldg 1501
Lantana, FL 33462
Phone: (800) 965-7767
FAX: (561) 965-7933
Email: <a href="/cdn-cgi/l/email-protection#b9d0d7dfd6f9c9dbd8c9d097dad6d4"><span class="__cf_email__" data-cfemail="ee87808881ae9e8c8f9e87c08d8183">[email&#160;protected]</span></a>
Website: <a href="http://www.pbapi.com">www.pbapi.com</a>
Contact: Will Burbage

    Other FAA approved repair facilities may be used.

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 August 15, 2001.
David A. Downey,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 01-21749 Filed 8-28-01; 8:45 am]
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