Lycoming has issued an important Mandatory Service Bulletin that affects a number of (L)O-360, (L)IO-360 and AEIO-360 as well as O-540, IO-540, AEIO-540 and TIO-540 engines. Those engines involved with this SB will require removal and crankshaft replacement at Lycoming's expense. Applicable portions of Lycoming's documents are reproduced below... please see the referenced URLs at the end of this story for more information.

SUBJECT: Crankshaft Replacement in Lycoming Engines.

MODELS AFFECTED: Any Lycoming engine model specified below manufactured, rebuilt, overhauled or repaired after March 1, 1999:
Lycoming O-540, IO-540, AEIO-540 and TIO-540 engines rated at 290 horsepower or lower as described in Section 1 and listed in Table 1.
Lycoming IO-540-P, -S, -AA engines rated at 250-290 horsepower by Lycoming as described in Section 2 and listed in Table 2.
Lycoming IO-540 and AEIO-540 engines rated at 300 horsepower as described in Section 2 and listed in Table 2.
Lycoming counterweighted (L)O-360, (L)IO-360 and AEIO-360 engines rated at any horsepower as described in Section 3 and listed Table 3.
Lycoming crankshafts with a crankshaft serial number listed in Table 4 shipped as a spare after March 1, 1999. These crankshafts may be installed in any of the engine models listed above.

NOTE: Engines that have complied with Service Bulletin No. 552 or Service Bulletin No. 553 are not affected by this Service Bulletin.

TIME OF COMPLIANCE: Within next 50 hours of operation or 6 months from the date of this Service Bulletin, whichever occurs first.
Lycoming has continued to analyze crankshafts in service. This analysis indicates that replacement of certain crankshafts is warranted. Therefore, Lycoming is recalling certain crankshafts in the specified four and six cylinder engines.
All affected Lycoming crankshafts have a serial number format of “V5379” followed by a 3 to 5 digit number and are listed in Table 4. Please note that not all “V5379” crankshafts are affected. The crankshaft serial number is marked on the O.D. of the propeller mounting flange.

NOTE: 1. The engine model, engine serial number, date of engine manufacture, and horsepower rating can be found in the engine logbook or on the engine data plate. This information will be required to determine if your engine is affected.
2. Some field repair stations mark their own identification (numbers and/or letters) on the propeller flange O.D. These numbers are not related to any Lycoming information.
3. For reference purposes, other Lycoming crankshaft serial number formats include the following:
a. An “I” followed by 5 digits.
b. A “V” followed by a 3 to 5 digit number.
c. A number from 3 to 6 digits.
Crankshafts with these serial numbers are not affected by this Service Bulletin.

MODEL DESCRIPTIONS:

SECTION 1
Any Lycoming engine model specified below manufactured, rebuilt, overhauled or repaired after March 1, 1999:
Lycoming O-540, IO-540, AEIO-540 and TIO-540 engines rated at 290 horsepower or lower with serial numbers as listed in Table 1.
Any overhauled or repaired Lycoming O-540, IO-540, AEIO-540 or TIO-540 engine rated at 290 horsepower or lower that has had a crankshaft replaced after March 1, 1999 with a crankshaft serial number listed in Table 4.

SECTION 2
Any Lycoming engine model specified below manufactured, rebuilt, overhauled or repaired after March 1, 1999:
Lycoming IO-540-P, -S, -AA engines rated at 250-290 horsepower by Lycoming with serial numbers as listed in Table 2.
Lycoming IO-540 and AEIO-540 engines rated at 300 horsepower with serial numbers as listed in Table 2.
Any overhauled or repaired Lycoming IO-540-P, -S, -AA rated at 250-290 horsepower by Lycoming or Lycoming IO-540 or AEIO-540 engine rated at 300 horsepower that has had a crankshaft replaced after March 1, 1999 with a crankshaft serial number listed in Table 4.

SECTION 3
Any Lycoming engine model specified below manufactured, rebuilt, overhauled or repaired after March 1, 1999:
Lycoming counterweighted (L)O-360, (L)IO-360 and AEIO-360 engines rated at any horsepower with serial numbers as listed in Table 3.
Any overhauled or repaired Lycoming counterweighted (L)O-360, (L)IO-360 or AEIO-360 engine that has had a crankshaft replaced after March 1, 1999 with a crankshaft serial number listed in Table 4.

NOTE: The counterweighted 360 engines can be identified by the #6 as the 4th suffix character in the engine model (Example: IO-360-A1B6).

INSTRUCTIONS FOR COMPLIANCE:

1. If your Lycoming engine serial number is listed in the Table for your engine model (Table 1, 2 or 3), before 50 hours or 6 months, whichever occurs first, contact Lycoming by phone at 570-323-6181 or by fax at 570-327-7160 to schedule return of the engine for crankshaft replacement.
2. If your engine model was overhauled, repaired, or had the crankshaft replaced after March 1, 1999, verify the crankshaft serial number through pertinent aircraft/engine documentation or overhaul/maintenance facility records. The engine logbook may contain crankshaft replacement and serial number information. If your crankshaft serial number is listed in appropriate Table 4, contact Lycoming by phone at 570-323-6181 or by fax at 570-327-7160 to schedule return of the engine for crankshaft replacement. If your crankshaft serial number cannot be verified through engine records, contact Lycoming.
3. Crankshafts listed in Table 4 must not be reused to assemble any engine. Check any uninstalled crankshaft against Table 4. If a subject crankshaft is found, contact Lycoming.
4. After you determine that your engine and crankshaft are not affected by this Service Bulletin, make appropriate logbook entries.
5. Factory replacement of the crankshafts listed in Table 4 will be accomplished at no cost to the owner.
Labor for engine removal and reinstallation, when authorized by Lycoming, will be reimbursed in accordance with the current revision of Removal and Installation Labor Allowance Guidebook, SSP-875 through an authorized Lycoming Distributor, using the standard Warranty procedure.

Excerpt From Lycoming SB 566 Customer Letter

In 2002, Lycoming issued three Service Bulletins relating to crankshafts in turbocharged engines rated at 300 hp and higher. Approximately 950 engines were removed from service pursuant to these Service Bulletins. The crankshafts in these engines were replaced with crankshafts forged with a different process and specific FAA-approved process controls designed to verify compliance with Lycoming’s specification. Lycoming has recently certified and gained FAA approval of a new forging supplier, which will use the same enhanced process controls.

Lycoming and the FAA have continued to monitor closely and analyze the service performance of engine models equipped with crankshafts made with the same process as those affected by the earlier Service Bulletins. Though our analysis is still ongoing, it appears that the same condition that prompted the 2002 Service Bulletins could be adversely affecting the performance of certain engines outside of the scope of those Bulletins. Lycoming continues to monitor the performance of its engines and, consistent with our strong commitment to flight safety, will continue to take whatever measures are necessary for safety and reliability.

Service Bulletin 566 requires crankshaft removal within the next fifty (50) flight hours or within six (6) months, whichever comes first. The affected crankshafts and engines are identified in the Bulletin.

Contact Lycoming at 1-800-258-3279 or outside the United States at 570-323-6181 and follow the menu instructions, or by fax at 570-327-7160 to schedule the return of your engine.

When Lycoming receives your engine it will be disassembled, inspected and scheduled for reassembly that includes an approved crankshaft and new bearings. We will warrant this work on your engine for twelve (12) months, with the start date of the warranty being two weeks from the date the engine is shipped back to you, after compliance with this Bulletin, subject to the standard warranty restrictions.

Lycoming will pay inbound and outbound freight via Lycoming’s specified LTL carrier. Removal and re-installation of the engine will be reimbursed per the Removal and Installation Labor Allowance Guide Book (SSP-875) through an authorized Lycoming distributor.

Lycoming will prioritize the engine repairs as follows:
1. Federal, State and Municipal facilities, especially those involved in Homeland Security;
2. FAR Part 121 operators (scheduled carriers);
3. FAR Part 135 operators (commuter and on-demand operations);
4. FAR Part 91 and 141 operators (flight training and general operations).

We apologize for the inconvenience to you. We will continue to exert our best efforts to meet our commitments to you: quality, reliability and service.

Again, if you have any questions, please contact us at the Lycoming Engines Service Department: Lycoming Customer Service 800 number 1-800-258-3279; outside the US 1-570-323-6181 or fax 1-570-327-7160.

FMI: www.lycoming.textron.com/main.jsp?bodyPage=serviceBulletin566/index.html, www.lycoming.textron.com/support/publications/maintenancePublications/serviceBulletins/SB566.pdf