[Federal Register Volume 65, Number 23 (Thursday, February 3, 2000)]
[Rules and Regulations]
[Pages 5238-5241]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-2085]



[[Page 5238]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-133-AD; Amendment 39-11536; AD 2000-02-18]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-100, -200, -300, -400, 
and -500 Series Airplanes

AGENCY:  Federal Aviation Administration, DOT.

ACTION:  Final rule.

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SUMMARY:  This amendment supersedes an existing airworthiness directive 
(AD), applicable to certain Boeing Model 737-100, -200, -300, -400, and 
-500 series airplanes; that currently requires an inspection of 
reworked aileron/elevator power control units (PCU's) and rudder PCU's 
to determine if reworked PCU manifold cylinder bores containing chrome 
plating are installed, and replacement of the cylinder bores with 
cylinder bores that have been reworked using the oversize method or the 
steel sleeve method, if necessary. This amendment, among other items, 
expands the applicability of the existing AD to include airplanes 
equipped with certain rudder PCU's. This amendment is prompted by a 
review of the design of the flight control systems on Model 737 series 
airplanes. The actions specified by this AD are intended to prevent a 
reduced rate of movement of the elevator, aileron, or rudder due to 
contamination of hydraulic fluid from chrome plating chips; such 
reduced rate of movement, if not corrected, could result in reduced 
controllability of the airplane.

DATES:  Effective March 9, 2000.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of March 9, 2000.

ADDRESSES:  The service information referenced in this AD may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the Federal 
Aviation Administration (FAA), Transport Airplane Directorate, Rules 
Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of 
the Federal Register, 800 North Capitol Street, NW., Suite 700, 
Washington, DC.

FOR FURTHER INFORMATION CONTACT:  Don Kurle, Senior Engineer, Systems 
and Equipment Branch, ANM-130S, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2798; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION:  A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) by superseding AD 97-09-14, 
amendment 39-10010 (62 FR 24008, May 2, 1997); which is applicable to 
certain Boeing Model 737-100, -200, -300, -400, and -500 series 
airplanes; was published as a supplemental notice of proposed 
rulemaking (NPRM) in the Federal Register on April 26, 1999 (64 FR 
20226). The action proposed to continue to require an inspection of 
reworked aileron/elevator power control units (PCU) and rudder PCU's to 
determine if reworked PCU manifold cylinder bores containing chrome 
plating are installed, and replacement of the cylinder bores with bores 
that have been reworked using the oversize method or the steel sleeve 
method, if necessary. The action also proposed to require expanding the 
applicability of the existing AD to include airplanes equipped with 
certain rudder PCU's.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Support for the Supplemental NPRM

    One commenter states that it supports the supplemental NPRM and 
will be able to meet the requirements as proposed.

Request To Revise Applicability Statement

    One commenter recommends that the order of applicability should be 
reversed to ``serial number less than xxx, except those with `ss','' to 
minimize confusion.
    The FAA concurs with the intent of the commenter's request. The FAA 
concurs that the applicability statement in the supplemental NPRM may 
be confusing to operators. However, the FAA finds that it would be more 
clear to state only what serial numbers are excluded from the 
applicability of the AD, rather than stating certain serial numbers 
that are included as well as certain serial numbers that are excluded 
from the applicability of this AD. Therefore, the applicability 
statement of this final rule has been revised to state that this AD 
applies to ``Model 737-100, -200, -300, -400, and -500 series 
airplanes; * * * equipped with:
     A rudder power control unit (PCU), having part number (P/
N) 65-44861-( ), P/N 65C37052-( ), or P/N 65C37053-( ), except those 
having a serial number of 1252A or greater or having a serial number 
that contains `ss'; or
     An aileron or elevator PCU having P/N 65-44761-( ), except 
those having a serial number of 5360A or greater or having a serial 
number that contains `ss.' ''
    In addition, paragraphs (a) and (d) of this final rule have been 
revised similarly.

Request To Clarify Acceptable Methods of Inspection

    Two commenters request that the wording of paragraph (a) of the 
supplemental NPRM be revised to clarify the FAA's intent. The 
commenters point out that paragraph (a) of the supplemental NPRM reads, 
``Perform an inspection of reworked or overhauled aileron and elevator 
PCU's * * * in accordance with Boeing Service Letter 737-SL-27-30, 
dated April 1, 1985.'' The commenters state that Boeing Service Letter 
737-SL-27-30 does not contain information on means of inspection of PCU 
cylinder bores that have been reworked or repaired using chrome 
plating. One of the commenters recommends that determination of whether 
cylinder bores have chrome plating should be based on either 
maintenance records or physical inspection of the PCU's. The other 
commenter recommends that, to prevent confusion, paragraph (a) be 
revised to read, ``Perform an inspection of reworked or overhauled 
PCU's to determine if reworked manifold bores containing chrome plating 
as described in Boeing Service Letter 737-SL-27-30 are installed * * 
*.'' The commenters state that these recommendations are also 
applicable to paragraph (d).
    The FAA concurs with the commenters' request. Paragraph (a) has 
been revised to clarify acceptable methods to determine whether the PCU 
cylinder bores have chrome plating. Paragraph (a)(1) has been added to 
the final rule to allow inspection of maintenance records to determine 
whether the PCU has a chrome-plate-repaired cylinder bore.
    Paragraphs (a)(1)(i), (a)(1)(ii), (a)(1)(iii), and (a)(1)(iv) 
identify criteria that demonstrate that a PCU does not have a chrome-
plated cylinder bore.
    Paragraph (a)(2) has been added to specify a physical inspection of 
the PCU to detect vibroengraved text ``737-SL-27-30'', as evidence of 
prior inspection to verify that the PCU does not contain a cylinder 
bore repaired with chrome plating.
    Paragraph (a)(3) has been added to specify performance of the PCU

[[Page 5239]]

Non-Destructive Test (NDT) as identified in Boeing Service Letter 737-
SL-27-120, dated January 28, 1998.
    Compliance times for performance of the requirements of AD 97-09-
14, which were contained in paragraphs (a)(1) and (a)(2) of the 
supplemental NPRM, are unchanged, but have been incorporated within 
paragraph (a) of the final rule.
    Paragraph (d) of the final rule has been revised to be similar to 
the revised paragraph (a) and to refer to paragraphs (a)(1), (a)(2), 
and (a)(3) for inspection instructions.

Request for Explicit Approval of NDT Inspection

    One commenter requests that the NDT inspection noted in Boeing 
Service Letter 737-SL-27-120 be expressly approved as meeting the 
requirements of paragraphs (a) and (d) of the proposed AD. The 
commenter states that it believes that this is preferable to the 
wording of the supplemental NPRM, which states that alternative methods 
of compliance, approved previously in accordance with AD 97-09-14 are 
approved as alternative methods of compliance for this AD.
    The FAA concurs with the intent of the commenter's request. As 
stated previously, paragraph (a)(3) has been added to list the NDT 
inspection method noted in Boeing Service Letter 737-SL-27-120 as an 
approved method to determine the presence of chrome plating. No 
additional change to the rule is necessary in this regard.

Request To Revise Means of Compliance

    One commenter requests that paragraph (b) of the proposed rule be 
revised to allow replacement of the PCU in accordance with the 
operator's FAA-approved maintenance procedures for removal and 
installation of the affected aileron and elevator PCU's and rudder 
PCU's. The commenter states that reference to the Boeing Airplane 
Maintenance Manual as the means for removal and replacement of an 
affected PCU may result in difficulties for operators, because their 
approved means of airplane maintenance may not be the Boeing 737 
Airplane Maintenance Manual. (An individual operator has the option to 
develop its own FAA-approved maintenance program.)
    The FAA concurs with the commenter's request. Paragraphs (b) and 
(e) of this AD have been revised to add an option to perform the 
replacement of the PCU in accordance with procedures in the operator's 
FAA-approved maintenance program that are equivalent to the Boeing AMM 
procedures.

Request To Replace PCU Instead of Cylinder Bore

    One commenter requests that paragraph (b)(1) be revised to require 
replacement of the PCU with a PCU that does not have a chrome-plate-
repaired cylinder bore, instead of requiring replacement of the 
cylinder bore. The commenter cites no rationale for its request. 
Additionally, the commenter requests that the requirement be revised to 
allow use of any PCU that has been confirmed to not contain a chrome-
plated cylinder bore. The commenter states that the request to revise 
paragraph (b)(1) is also applicable to paragraph (e)(1) of the AD.
    The FAA concurs with the commenter's request. The FAA finds that it 
is not possible to remove the cylinder bore without removing the PCU 
from the airplane. Paragraphs (b)(1) and (e)(1) have been revised to 
require replacement of any PCU with a chrome-plate-repaired cylinder 
bore with a PCU that does not have a chrome-plate-repaired cylinder 
bore, instead of replacement of the chrome-plate-repaired cylinder 
bores.

Request To Correct Typographical Error

    One commenter requests that the reference to ``a PCU having serial 
number of 5306A or higher'' in paragraph (b)(2) of the supplemental 
NPRM be revised to reflect the correct serial number, which is 5360A or 
higher. The FAA concurs, and has corrected paragraph (b)(2) to refer to 
serial number 5360A or higher.

Request To Revise Spares Paragraphs

    One commenter requests that paragraphs (c) and (f) of the 
supplemental NPRM be revised to refer to units that are defined as 
acceptable for installation per paragraphs (b) and (e), respectively, 
of the AD. The commenter states that Boeing Service Letter 737-SL-27-30 
does not define inspection criteria, and the definition of acceptable 
units is not complete in the supplemental NPRM.
    The FAA concurs with the commenter's request. Paragraphs (c) and 
(f) have been revised to refer to units eligible as replacement PCU's 
per paragraphs (b) and (e), respectively.

Request To Allow PCU Disassembly and Inspection of Cylinder Bore

    One commenter requests that the proposed AD be revised to allow an 
option to perform PCU disassembly and inspection of the cylinder bore 
for chrome plating as an alternative to the NDT of the PCU, which, as 
stated previously, is specified in paragraph (a)(3) of the final rule.
    The FAA does not concur with the commenter's request. The 
manufacturer has not provided the FAA with any specific requirements or 
instructions to perform such an inspection. Therefore, the FAA cannot 
include such an option in the AD. However, operators that wish to 
perform PCU disassembly and inspection of the cylinder bore for chrome 
plating as an alternative to the NDT of the PCU specified in paragraph 
(a)(3) of this AD, may request approval of a method of and criteria for 
such disassembly and inspection as an alternative method of compliance, 
in accordance with paragraph (g)(1) of the AD.

Explanation of Additional Change From the Supplemental NPRM

    Paragraphs (b) and (e) of the supplemental NPRM state that the 
actions specified in those paragraphs are to be accomplished in 
accordance with certain chapters of the Boeing Airplane Maintenance 
Manuals. The FAA finds that specific revisions of the airplane 
maintenance manuals are not required for accomplishment of the actions 
specified in those paragraphs. Therefore, paragraphs (b) and (e) of 
this AD have been revised to call for use of certain chapters of the 
Boeing Airplane Maintenance Manuals as guidance for procedures to 
replace the PCU's.

Conclusion

    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 previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Cost Impact

    There are approximately 2,675 Model 737 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 1,091 
airplanes of U.S. registry will be affected by this AD.
    The actions that are currently required by AD 97-09-14 take 
approximately 5 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact of the currently required actions on U.S. operators is estimated 
to be $327,300, or $300 per airplane.
    The new actions that are required by this new AD will take 
approximately 5

[[Page 5240]]

work hours per airplane to accomplish, at an average labor rate of $60 
per work hour. Based on these figures, the cost impact of the new 
requirements of this AD on U.S. operators is estimated to be $327,300, 
or $300 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the requirements of this 
AD action, and that no operator would accomplish those actions in the 
future if this AD were not adopted.

Regulatory Impact

    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.
    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 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 location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, 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 39-10010 (62 FR 
24008, May 2, 1997), and by adding a new airworthiness directive (AD), 
amendment 39-11536, to read as follows:

2000-02-18  Boeing: Amendment 39-11536. Docket 97-NM-133-AD. 
Supersedes AD 97-09-14, Amendment 39-10010.

    Applicability: Model 737-100, -200, -300, -400, and -500 series 
airplanes; certificated in any category; equipped with:
     A rudder power control unit (PCU), having part number 
(P/N) 65-44861-(D),     P/N 65C37052-( ), or P/N 65C37053-( ), 
except those having a serial number of 1252A or greater or having a 
serial number that contains ``ss''; or
    An aileron or elevator PCU having P/N 65-44761-( ), 
except those having a serial number of 5360A or greater or having a 
serial number that contains ``ss.''

    Note 1:
    This AD applies to each airplane 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 airplanes 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)(1) 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 a reduced rate of movement of the elevator, aileron, 
or rudder, which, if not corrected, could result in reduced 
controllability of the airplane, accomplish the following:

Partial Restatement of Requirements of AD 97-09-14

    (a) Within 5 years or 15,000 flight hours after June 6, 1997 
(the effective date of AD 97-09-14, amendment 39-10010), or at the 
next time the PCU is sent to a repair facility, whichever occurs 
first: Perform an inspection of aileron and elevator PCU's having P/
N 65-44761-( ), except those having a serial number of 5360A or 
greater or having a serial number that contains ``ss''; and rudder 
PCU's having P/N 65-44861-( ), except those having a serial number 
of 1252A or greater or having a serial number that contains ``ss''; 
to determine whether a PCU manifold has a reworked or repaired 
cylinder bore(s) containing chrome plating. Accomplish this 
inspection as specified in paragraph (a)(1), (a)(2), or (a)(3) of 
this AD.
    (1) Inspect the airplane maintenance records to determine 
whether a PCU with a chrome-plate-repaired cylinder bore is 
installed. If inspection of the maintenance records shows that the 
PCU meets one of the criteria specified in paragraph (a)(1)(i), 
(a)(1)(ii), (a)(1)(iii), or (a)(1)(iv) of this AD, no further action 
is required by this AD for that PCU.
    (i) The PCU has never been reworked or repaired.

    Note 2:
    Chrome plating of the cylinder bores was limited to repair and was 
not used for new manufacture of PCU's or replacement manifolds.


    (ii) The PCU has been reworked or repaired, but chrome plating 
was not used as the means of PCU cylinder bore repair.
    (iii) The PCU has been reworked or repaired, but a manifold 
manufactured after December 31, 1985, was used to replace the 
cylinder bore.

    Note 3:
    No PCU manifold manufactured after December 31, 1985, was reworked 
or repaired using chrome plating.


    (iv) The PCU has been reworked or repaired using chrome plating 
of the cylinder bore, but the cylinder bore has subsequently been 
reworked to remove the chrome plating using the cylinder bore 
oversize method or steel sleeve method specified in Boeing Service 
Letter 737-SL-27-30, ``Aileron/Elevator and Rudder Power Control 
Unit Cylinder Bore Rework,'' dated April 1, 1985.
    (2) Inspect the PCU to determine whether the PCU is marked with 
vibroengraved text ``737-SL-27-30'' as evidence of prior inspection, 
as specified in Boeing Service Letter 737-SL-27-120,'' Aileron, 
Elevator, and Rudder Power Control Unit Cylinder Bore Material 
Identification Method,'' dated January 28, 1998.
    (3) Perform the PCU Non-Destructive Test (NDT) in accordance 
with Boeing Service Letter 737-SL-27-120, dated January 28, 1998, to 
determine whether chrome plating exists on the cylinder bore 
surface.

Replacement Required by AD 97-09-14

    (b) If any reworked PCU manifold cylinder bores containing 
chrome plating are found to be installed during the inspection 
required by paragraph (a) of this AD: Prior to further flight, 
accomplish the actions specified in paragraph (b)(1), (b)(2), 
(b)(3), or (b)(4) of this AD, using as guidance the following 
procedures of the Boeing 737 Airplane Maintenance Manual, as 
applicable: Chapter 27-11-71 (for Model 737-100, -200, -300, -400, 
and -500 series airplanes), Chapter 27-31-101 (for Model 737-100 and 
-200 series airplanes), or Chapter 27-31-14 (for Model 737-300, -
400, and -500 series

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airplanes), or equivalent procedures in the operator's FAA-approved 
maintenance program.
    (1) Replace the PCU with a PCU with cylinder bores that were 
manufactured after December 31, 1985, or with a PCU with cylinder 
bores that have been reworked using the oversize method or the steel 
sleeve method specified in Boeing Service Letter 737-SL-27-30, dated 
April 1, 1985.
    (2) Replace the aileron or elevator PCU with a PCU containing 
the letters ``ss'' in its serial number or with a PCU having a 
serial number of 5360A or higher.
    (3) Replace the rudder PCU with a PCU containing the letters 
``ss'' in its serial number or with a PCU having a serial number of 
1252A or higher.
    (4) Replace the PCU with a PCU for which paragraph (a) of this 
AD specifies that no further action is required.

Spares

    (c) As of June 6, 1997, no person shall install a manifold 
cylinder bore containing chrome plating, or an aileron or elevator 
PCU having P/N 65-44761-( ) that has a manifold cylinder bore 
containing chrome plating, or a rudder PCU having P/N 65-44861-( ) 
that has a manifold cylinder bore containing chrome plating, on any 
airplane, unless the PCU is eligible as a replacement PCU, as 
specified in paragraph (b) of this AD.

New Requirements of This AD

Inspection

    (d) Within 5 years or 15,000 flight hours after the effective 
date of this AD, or at the next time the PCU is sent to a repair 
facility, whichever occurs first: Perform an inspection of any 
rudder PCU having P/N 65C37052-    ( ) or P/N 65C37053-( ), except 
those having a serial number of 1252A or greater or having a serial 
number that contains ``ss,'' to determine if the PCU manifold has a 
reworked or overhauled cylinder bore(s) containing chrome plating. 
Perform the inspection in accordance with paragraph (a)(1), (a)(2), 
or (a)(3) of this AD.

Replacement

    (e) If any reworked or overhauled PCU manifold cylinder bores 
containing chrome plating are found to be installed during the 
inspection required by paragraph (d) of this AD: Prior to further 
flight, accomplish the actions specified in paragraph (e)(1), 
(e)(2), or (e)(3) of this AD, using, as guidance, procedures 
specified in Chapter 27-21-91 Boeing 737 Airplane Maintenance Manual 
(for Model 737-100, -200, -300, -400, and -500 series airplanes), or 
equivalent procedures in the operator's FAA-approved maintenance 
program.
    (1) Replace the PCU with a PCU with cylinder bores that were 
manufactured after December 31, 1985, or with a PCU with cylinder 
bores that have been reworked using the oversize method or the steel 
sleeve method specified in Boeing Service Letter 737-SL-27-30, dated 
April 1, 1985.
    (2) Replace the rudder PCU with a PCU containing the letters 
``ss'' in its serial number or with a PCU having a serial number of 
1252A or higher.
    (3) Replace the rudder PCU with a rudder PCU for which paragraph 
(a) of this AD specifies that no further action is required.

Spares

    (f) As of the effective date of this AD, no person shall install 
a rudder PCU having     P/N 65C37052-(  ) or P/N 65C37053-(  ) that 
has a manifold cylinder bore containing chrome plating, on any 
airplane, unless the PCU is eligible as a replacement PCU per 
paragraph (e) of this AD.

Alternative Methods of Compliance

    (g)(1) 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, Seattle Aircraft Certification 
Office (ACO), FAA, Transport Airplane Directorate. Operators shall 
submit their requests through an appropriate FAA Principal 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Seattle ACO.
    (2) Alternative methods of compliance, approved previously for 
AD 97-09-14, amendment 39-10010, are approved as alternative methods 
of compliance with this AD.

    Note 4:  Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Manager, Seattle ACO.

Special Flight Permits

    (h) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.

Incorporation by Reference

    (i) The PCU NDT shall be done in accordance with Boeing Service 
Letter 737-SL-27-120, dated January 28, 1998. This incorporation by 
reference was approved by the Director of the Federal Register in 
accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, 
Seattle, Washington 98124-2207. Copies may be inspected at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington; or at the Office of the Federal Register, 800 North 
Capitol Street, NW., Suite 700, Washington, DC.
    (j) This amendment becomes effective on March 9, 2000.

    Issued in Renton, Washington, on January 24, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-2085 Filed 2-2-00; 8:45 am]
BILLING CODE 4910-13-U