# ALERT SERVICE BULLETIN MBB BK117 C-2

CHANGE INSTRUCTION NO. 2 FOR MBB BK117 C-2-04A-005

PAGE 1 of 1 2010-04-28 Date: First issue: 2009-06-08 Revision 01: 2009-06-22 Revision 02: 2010-04-28

Please replace Alert Service Bulletin MBB BK117 C-2-04A-005 with Revision 02.

With Revision 02 the following bevel gear S/Ns are added: S/N 1039, 1065, 1113, 1129 and S/N 1156. If the previous issue of this Alert Service Bulletin has already been accomplished, the intermediate transmission must be checked for the installed bevel gear S/Ns that have been added with Revision 2.

# ALERT SERVICE BULLETIN MBB BK117 C-2

MBB BK117 C-2-04A-005 PAGE 1 of 5 2009-06-08 REVISION 02, 2010-04-28 

# AirworthinessLimitations – Tail Rotor – Reduction of the life time of certain bevel gears
1. Planning Information A. Effectivity (1) Helicopters affected: All MBB BK117 C-2. (2) Components affected: Intermediate transmission P/N 4639 002 007 with bevel gears P/N 4639 310 065 ofserial numbers i.a.w. attached Table 1. (3) Spare Parts affected: Intermediate transmission P/N 4639 002 007 with bevel gears P/N 4639 310 065 ofserial numbers i.a.w. attached Table 1. B. Concurrent Requirements Not applicable.
C. Reason On bevel gear production batch numbers tooth foot fillets had been detected which were below theminimum values required in the design documents. Calculations have shown that this decreases the life limit of the bevel gears. Therefore, with this Alert Service Bulletin the life limit of the affected bevel gears 4639 310 065 is reduced. D. Description Determinethe current Flight Hours (fh) of the af fected bevel gears. Enter changed life limits in the list of life–limited parts and in the log card. Determine the remaining life of the bevel gears and if necessary replace the bevel gears (intermediate gear box). Fill out reply form sheet and send it to ECD. E. Compliance (1) The current life limits of the affected bevel gears 4639 310 065 must be determined immediately after the receipt of this Alert Service Bulletin and the changed life limits must be entered in the list of life–limited parts and in the log card of the intermediate transmission. (2) If the revised allowable life limit has already been exceeded, only a ferry flight up to a maximum of 20fh to the maintenance facility is allowed. After this the component must be replaced. (3) For intermediate gear boxes fitted with the affected bevel gears, P/N 4639 310 065, that have not reached the revised allowable life limit the gear boxes may remain in service until life limit of the bevel gear is reached. The intermediate gear box must be sent to a certified overhaul facility for bevel gear replacement.

Thisdocument is available on the internet: www .eurocopter.com/techpub

# ALERT SERVICE BULLETIN MBB BK117 C-2

MBB BK117 C-2-04A-005 PAGE 2 of 5 REVISION 02, 2010-04-28 2009-06-08 F. Approval The technical content of this document is approved under the authority of DOA No. EASA.21J.034. G. Manpower Not applicable. H. Weight and Balance Not applicable.

I. Electrical Load Data Not applicable. J. Software Accomplishment Summary Not applicable.

K. References Not applicable. L. Other publications affected Not applicable. M. Interchangeability of Parts Not applicable.



## 2. Material Information
A. Material – Price and Availability Not applicable. B. Support Information Not applicable. C. Material Necessary for Each Helicopter Not applicable. D. Material Necessary for Each Spare Not applicable.

# ALERT SERVICE BULLETIN MBB BK117 C-2

MBB BK117 C-2-04A-005 PAGE 3 of 5 2009-06-08 REVISION 02, 2010-04-28 E. Reidentified Parts Not applicable. F. Special Tooling Not applicable.



## 3. Accomplishment Instructions A. Determine serial number of the bevel gears 4639 310 065 installed in the intermediate transmission by consulting the log card of the intermediate transmission. (1) If a bevel gear with one of the serial numbers given in Table 1 is installed, take the associated life limit from the Table and make the following entry: (a) In the log card of the intermediate transmission: ”I.A.W.ASB MBB BK117 C-2-04A-005 Bevel gear S/N XXXX must be replaced by XXXX fh TSN”. (b) In the list of life–limited parts: Life limit of bevel gear 4639 310 065 with S/N xxxx is xxxx fh. (2) Copy reply form sheet on page 5, fill out and send to ECD. (3) If the bevel gear S/N is not listed in Table 1, make the following entry: In the log card of the intermediate transmission: ”I.A.W. ASB MBB BK117 C-2-04A-005 bevel gear is not affected by this bulletin”.



## 4. Appendix Table 1: Assignment of bevel gear’s S/N to life limit Reply form sheet

# ALERT SERVICE BULLETIN MBB BK117 C-2

MBB BK117 C-2-04A-005 PAGE 4 of 5 REVISION 02, 2010-04-28 2009-06-08 Table 1:Assignment of bevel gear’s S/N to life limit Bevel gear S/N Life limit (Fh) Bevel gear S/N Life limit (Fh) 1012 3400 1091 1500 1015 3400 1092 1500 1016 3400 1093 1500 1023 3400 1094 1500 1026 2900 1095 1500 1028 2900 1096 1500 1029 2900 1097 1500 1031 2900 1098 1500 1035 2900 1099 1500 1037 2900 1100 1500 1038 2900 1101 1500 1039 2900 1102 1500 1040 2900 1103 1500 1041 2900 1104 1500 1043 2900 1108 1500 1044 2900 1113 1500 1045 2900 1128 1500 1048 1500 1129 1500 1049 1500 1130 1500 1050 1500 1145 1500 1051 1500 1148 1500 1053 1500 1154 3400 1054 1500 1156 3400 1055 1500 1157 3400 1056 1500 1158 3400 1057 1500 1159 3400 1059 1500 1160 3400 1061 1500 1161 3400 1062 1500 1162 3400 1063 1500 A1162 4100 1065 1500 1163 3400 1066 1500 1164 3400 1067 1500 A1164 4100 1068 1500 1165 3400 1069 1500 1166 3400 1070 1500 1167 3400 1072 1500 1168 3400 1073 1500 1169 3400 1074 1500 1170 3400 1075 1500 1171 3400 1076 1500 1172 3400 1077 1500 1173 3400 1078 1500 1174 3400 1079 1500 A1174 4100 1080 1500 1175 3400 1082 1500 1176 3400 1084 1500 1177 4100 1085 1500 1178 4100 1086 1500 1179 4100 1087 1500 4004 4100 1089 1500 1090 1500

# ALERT SERVICE BULLETIN MBB BK117 C-2

MBB BK117 C-2-04A-005 PAGE 5 of 5 2009-06-08 REVISION 02, 2010-04-28 

# Telefax

To Eurocopter Deutschland GmbH Customer Support FAX 0049 906 714111

Operator’s address:

Date:__________ Signature:___________________ Accomplishment Confirmation Form In order to be able to ensure an on–time availabilty of the bevel gears, we need your support. Therefore, we ask you to fill out this reply form sheet and send it to ECD. Thank you!

The following helicopter is affected by ASB MBB BK117 C-2-04A-005:

Please make a copy of this page! The original of this page is to remain in the ASB! Helicopter S/N: Intermediate transmission S/N: TT intermediate transmission: Flight hours per year approx.:

Bevel gear S/N: Bevel gear TSN: