AD 99-01-08

This amendment adopts a new airworthiness directive (AD) that is applicable to Pratt & Whitney (PW) JT8D and JT3D series turbofan engines. This action requires operators to remove and replace with serviceable parts, certain stage 7 through stage 15 high-pressure compressor (HPC) disks identified by part number and serial number. This amendment is prompted by a report of an uncontained failure of a stage 8 HPC disk during a takeoff roll that resulted in damage to the airplane. The actions specified in this AD are intended to prevent the failure of a high-pressure compressor disk due to Cadmium embrittlement, resulting in uncontained engine failure and damage to the airplane.

Comments for inclusion in the Rules Docket must be received on or before March 1, 1999.

Final rule; request for comments.

99-01-08 Pratt & Whitney: Amendment 39-10975. Docket 98-ANE-77-AD.

Applicability: Pratt & Whitney (PW) JT8D and JT3D series turbofan engines, with stage 7 through stage 15 high-pressure compressor (HPC) disks installed, identified by part number (P/N) and serial number (S/N) specified in Appendix 1. These engines are installed on but not limited to the following aircraft: Boeing 707, 727, and 737 series airplanes and McDonnell Douglas DC-8, DC-9, and MD-80 series airplanes.

Appendix 1
Disk Part Number and Serial Number (Sorted By Disk Part Number)

Stage
Disk Part Number
Disk Serial Number
7
701407
7A7271
7
701507
4Z2030, 4Z2122, 8Z6454
7
766007
8B5265
7
774407
B207AA0307, B207AA0350, B207AA0379, B207AA0578, B207AA0643, BENCAH1353, BENCAH2320, BENCAH2327, BENCAH2851, BENCAH4091, BENCAJ8414, BENCAJ8440, BENCAK1631, BENCAK1684,BENCAK5135, BENCAK6623, BENCAK6643, BENCAK8115, H19093, H19026, H29904, J17128, J17407, J39120, J72011, J72132, K20050, K20167, K78491, L72139, M15364, M15368, M77985, M83784, M93463, N14127, N14190, N14213, N24114, N23978, N24091, N37879, N37919, N70390, N88161, N88195, N88335, N88342, N94974, N95036, P14716, P14741, P35486, P54563, P60347, P60394, P60446, P70328, P81247, P81253, P81392, P81399, P86295, P86311, R03089, R12413, R12418, R12549, R12557, R19365, R31290, R31411, R37414, R37520, R37554, R46834, R46893, R46918, R46943, R47019, R72171, R72257, S05566, S05610, S05659, S10014, S10050, S13885, S13910, S14048, S14063, S14088, S14173, S36633, S36810, S36857, S37128, S37149, S37168, S37187, S37312, S37367, S37389, S37420, S37469, S37498, T04409, T04526, T04566, T04615, T04632, T04898, T04899, T04988, T05055, T05106
7
5006007-01
B207AA0068, B207AA0693, BENCAH0061, BENCAH3134, BENCAJ8558, BENCAJ8594, BENCAL0749, BENCAL2650, R54586, R79450, S11202, S11206, S57118, S57216, S57519
7
5006007-02
BENCAK9643, BENCAK9690, BENCAK9697, BENCAK9705, BENCAK9723, BENCAL3657, BENCAL5478
7
774407
BENCAH0521, BENCAJ8454, R57626, T04885
8
738308
9B1363, H03990
8
748608
7A9608, 7B9489, 8B0397, B208AA0030, B208AA0045, B208AA0070, BENCAJ8185, G30014, G62624, G63907, H29599, H35085, H64390, H84992, H86520, J29857, J29958, J57418, J57426, J57469, J57532, J57660, J57663, J94763, J94815, M54646, M54770, M54821, M54843, N14562, N14765, N84308, N84314, N84317, N84319, N84373, N84418, P26025, P26136, P26153, P26171, P28471, P28530, P28534, P28564, P28596, P28607, P83853, P94736, P98927, R18995, R46153, R73850, S01136, S01153, S01185, S50692, S50748, S78016, S78066, S78128
8
787008
K51696, K52389, L61543, M76852, M77423, M77749, M77791, N33354, N33408, N33702, N33760, N89060, N89386, N90133, N90152
8
787008F
N89050
8
787208
B228AA0194, B228AA0343, B228AA0371, B228AA0540, B228AA0574, B228AA0605, BENCAH4505, BENCAH5428, BENCAH5435, BENCAJ5724, BENCAK0065, BENCAK0066, BENCAK6165, BENCAK6359, BENCAK8796, BENCAK9253, BENCAL1567, BENCAL1571, BENCAL1579, BENCAL1887, BENCAL3339 ,BENCAL5283,BENCAM0672, J47026, K12730, N06609, N89709, P43644, P43665, P43897, P43936, P43950, P43954, P44141, P44694, P45378, P45593, R23192, R23234, R23450, R23452, R23569, R23837, R24172, R24201, R24205, R24390, R24599, R24827, R91709, S07732, S39110, S39281, S39337, S39409, S39410, S39487, S39509, S39534, S39633, S39676, S39721, S39942, S39963, S39996, S40033, S40041
8
788608
H36177
8
788708
7A2254
8
789508
G51990
8
789608
J46995
8
792038
B228AA0331, B228AA0511, B228AA1005, BENCAJ8854, BENCAJ8871
8
796348
K53240
8
797938
BENCAL2605
8
5005808-01
B228AA0901, BENCAJ1138, BENCAJ8902, S70327
9
628209
5X8746
9
701509
8Z5256, 9A6145, H86825, J00245, J25666, J87515, J89031, K34309, K35061, K55559, K85824, L31209, L31751, L55770, M10469, M40027, M49712, M61566, M84762, M86342, M86842, M86844, N02758, N02994, N209AA0006, N209AA0080, N209AA0091, N209AA0094, N209AA0255, N209AA0339, N209AA0352, N209AA0561, N21068, N21507, N21508, N22475, N22570, N22591, N41297, N42662, N57120, N79874, N79893, N81317, N97653, NENCAH0017, NENCAH0187, NENCAH0192, NENCAH0222, NENCAH0269, NENCAH0280, NENCAH0337, NENCAH0422, NENCAH0445, NENCAH0451, NENCAH0593, NENCAH0737, NENCAH0757, NENCAH0913, NENCAH0920, NENCAH1014, NENCAH1227, NENCAH1357, NENCAH1430, P11360, P11370, P11443, P11450, P12878, P51572, P52444, P52971, P53248, P77028, P77207, P78457, P97645, P98143, P98661, P98961, P98991, R17442, R18113, R45676, R46466, R72941, R73009, R73013, R73420, R73464, R73467, R73804, R73934, S00689, S00741, S00777, S00798, S18975, S19201, S50490, S77602, S77616, S77651
9
739509
G79836
9
772509
H49185, K56788, P97497, R73983, S01209, S50832
9
798509
B209AA0539, BENCAH3770, BENCAJ9383, BENCAK9880, BENCAL0717, BENCAL0703, BENCAL2372, BENCAL6305
9
701509
BENCAH0448
9
701509N
R18236
9
772509
K23767
9
798509
BENCAJ9360, P53159
10
701410
7Z0800, 7Z0806
10
701810
0A0377, 3B8966, 3B9144, 9Z9847, A00862, H39339, H60642, R22292
10
701810G
G82663
10770510
4B4921, G80187
10
772510
B210AA0014, B210AA0202, B210AA0273, B210AA0637, B210AA0640, B210AA0749, B210AA0752, B210AA0429, BENCAH0251, BENCAH1404, BENCAJ9735, BENCAJ9784, BENCAJ9868, BENCAK5318, BENCAK5762, BENCAK5946, BENCAK9105, BENCAL0388, BENCAL1598, BENCAL1601, BENCAL2427, BENCAL4455, BENCAL5993, H34395, H58784, J23708, J68609, J87953, J88767, K03190, K03586, K24796, K25271, K35625, K55848, K66100, K68068, K85468, L15000, L56873, L84428, L86007, M10049, M10613, M39974, M56263, M61659, M84606, M87097, N03907, N02538, N02778, N03133, N21767, N22275, N41185, N41208, N41484, N41613, N42094, N42143, N42187, N42838, N57150, N57830, N57862, N80227, N80661, N80671, N81136, N81150, N81454, N81456, P11024, P11818, P11869, P12016, P12811, P51804, P51873, P52670, P53019, P53213, P76639, P77620, P77862, P78050, P97278, P98630, R17507, R18502, R18520, R44856, R44861, R44864, R45159, R46345, R72614, R72630, R72884, R73138, R73408, R73612, R73617, R73862, S01349, S01364, S01365, S01406, S01463, S01486, S19301, S19305, S19487, S19630, S50981, S51203, S70220, S78451, S78492, S78780, T18947, T19138, T19153, T49020, BENCAJ9732, N81125, S70249
11
701411
2B3335, 6Y6265, 6Y7124, 9Y4723
11
701811
A03782, G33309, H24029, J28340
11
701811D
5A8129
11
772511
B211AA0058, B211AA0106, B211AA0119, B211AA0240, B211AA0621, B211AA0744, B211AA0944, B211AA1224, B211AA1227, BENCAH4040, BENCAK0466, BENCAK7376, BENCAK7377, BENCAK7378, BENCAK7391, BENCAK7432, BENCAK7436, BENCAK7449, BENCAK7493, BENCAK7517, BENCAL2882, BENCAL2903, BENCAL3047, BENCAL3107, J23871, J60159, J60844, J88645, K23851, K25421, K34786, K35678, K56219, K86641, L30533, L31909, L84584, L85406, LI4848, M39922, M40288, M49491, M61348, M73855, M86390, N21317, N02565, N02849, N03254, N03566, N03749, N03884, N21373, N21747, N22005, N22023, N22361, N22749, N41265, N41900, N42762, N56596, N57211, N57249, N57915, N98569, N98918, N99538, P10980, P11984, P12374, P12389, P12900, P51911, P52733, P53057, P66436, P77051, P77157, P77977, P78064, P78528, P78566, R05712, R18713, R29689, R29849, R29855, R29858, R29957, R30079, R30091, R30098, R30396, R30540, R30753, R30778, R31032, R44897, R45822, R46094, R46488, S03919, S03920, S04110, S04209, S04340, S04487, S04565, S04576, S04601, S04625, S80671, S80726, S80801, S80817, S80830, T22255, T22427, T22430, T22433, T22695, T22711, T23028, B211AA0681, N97343
11
772511H
S03892
11
772511M
B211AA0066, B211AA0584
12
414212HC
5L5355
12
701412
1Z5717, 5Y5915
12
701812
1Z7175, 3A3910, A02080, H62635, N28026
12
701812D
G93483
12
717312
2B3418, G15036, G29488, G63557
12
769312
1Z5153
12
772512
H34015, H77074, J24654, J38490, J59514, K02314, K24837, K55637, K55648, K86189, L15523, L30268, L30307, L31553, L56280, L56328, L84937, L86244, M86432, M10163, M10415, M10948, M11260, M11282, M40263, M48887, M49046, M49595, M61285, M61856, M61955, M84903, M86222, N02391, N02431, N02488, N03222, N03686, N22344, N22883, N41245, N41249, N41463, N57445, N57460, N58065, N58102, N58109, N58117, N80256, N81365, N97115, N97124, N97457, N98208, N98222, N99001, N99066, P11199, P12270, P12312, P51405, P51433, P51437, P52633, P53139, P53173, P77109, P77978, P78005, P78202, P97472, P98163, P98509, P98706, P98876, R17547, R18000, R18009, R18395, R18404, R19046, R19047, R45120, R45947, R46042, R46055, R73153, R73459, R73782, R74102, R74120, R74356, R74528, S01701, S01720, S01963, S02019, S51348, S51376, S51391, S51490, S51499, S51540, S51542, S78919, S78924
12
798512
B212AA0948, B212AA0032, B212AA0209, B212AA0234, B212AA0255, B212AA0276, B212AA0283, B212AA0436, B212AA0439, B212AA0442, B212AA0497, B212AA0739, B212AA0788, B212AA0808, B212AA0826, B212AA1042, BENCAH1745, BENCAH2182, BENCAJ9560, BENCAJ9619, BENCAJ9680, BENCAK8619, BENCAK9455, BENCAL0437, BENCAL0445, BENCAL0446, BENCAL0450, BENCAL2451, BENCAL2462, BENCAL5111, BENCAL6030, R46125, S94444, S94463, S94550, T19384, T28481, T28560,T28581, T43085
12
772512
N97437
12
772512G
S02004
12
798512
BENCAJ9509, BENCAL2313, BENCAL6575
13
701813
9B6665, G92924, H10764, H63434, H63596
13
701813E
H40915
13
762413
T02660
14
750414
H91643, H92945, N68876, P95479, T39660
15
750115
H530181
15
750415
J35404, S97819

Note 1: This airworthiness directive (AD) applies to each engine 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 engines 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 (b) 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 the failure of a high-pressure compressor disk due to Cadmium embrittlement, resulting in uncontained engine failure and damage to the airplane, accomplish the following:

(a) Remove from service stage 7 through stage 15 high-pressure compressor (HPC) disks identified in Appendix 1 of this AD as follows:

(1) For disks with less than 250 hours time in service (TIS) since last NiCd plating, remove disk and replace with a serviceable part within 100 hours TIS after the effective date of this AD.

(2) For disks with greater than or equal to 250 hours and less than 500 hours TIS since last NiCd plating, remove disk and replace with a serviceable part within 150 hours TIS after the effective date of this AD.

(3) For disks with greater than or equal to 500 hours TIS since last NiCd plating no action is required.

(4) Disks removed from service in accordance withthis AD are not eligible for installation in any engine.

(b) 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, Engine Certification Office. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Engine Certification Office. Note 2: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Engine Certification Office.

(c) 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 aircraft to a location where the record search requirements of this AD can be accomplished.

(d) This amendment becomes effective on January 5, 1999.

The Federal Aviation Administration (FAA) has received a report of an uncontained failure of a stage 8 high-pressure compressor (HPC) disk, part number (P/N) 787008, installed on a Pratt & Whitney (PW) JT8D-9 turbofan engine. The laboratory testing revealed that the disk failed as a result of Cadmium embrittlement. Nickel-Cadmium (NiCd) coatings are used on JT8D and JT3D steel disks to inhibit corrosion. The coating process consists of many steps, the most fundamental of which are the electrolytic deposition of a Nickel base layer followed eventually by the electrolytic deposition of a Cadmium layer. The part is then baked in an oven. During the bake cycle the Nickel layer diffuses into the Cadmium which creates an alloy with a higher melting temperature than pure Cadmium and immobilizes the Cadmium to prevent the liquid metal embrittlement of the steel part. The Cadmium rich outer layer acts as the corrosion inhibitor. The diffused Nickel acts to immobilize the Cadmium and prevent Cadmium embrittlement of the steel. If the Nickel plating is not applied with sufficient thickness during the NiCd plating process, the undiffused Cadmium can attack the grain boundaries of the base metal. Failure results when the disk is exposed to engine operating temperatures and stresses. Analysis of this and other Cadmium embrittlement failures indicates that a disk exposed to Cadmium embrittlement will likely fail within 500 hours time-in-service (TIS). Based on the risks associated with a process anomaly at the repair facility that plated the disk, the FAA has determined that action is required to remove a number of disks plated at that facility since February 1996. The disks most at risk are those disks which have accumulated less than 500 hours TIS since they were last plated. Disks which have accumulated more than 500 hours TIS since plating will not be recalled by this AD. The FAA has identified stage 7 through stage 15 HPC disks by P/Nand serial number (S/N) that have been NiCd plated by the repair facility from February 1996 through October 1998. This condition, if not corrected, could result in the failure of a high-pressure compressor disk due to Cadmium embrittlement, resulting in uncontained engine failure and damage to the airplane.

Since an unsafe condition has been identified that is likely to exist or develop on other engines of the same type design, this AD is being issued to prevent the failure of a high-pressure compressor disk due to Cadmium embrittlement, resulting in uncontained engine failure and damage to the airplane. This AD requires removal and replacement of certain part-numbered and serial-numbered stage 7 through stage 15 HPC disks with serviceable parts.

Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days. Comments Invited

Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, andenergy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 98-ANE-77-AD." The postcard will be date stamped and returned to the commenter.

The regulations adopted herein will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES."

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, 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.

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