AirWard Lycoming MSB 388C Valve Guide Inspection Kit
Lycoming issued a Mandatory Service Bulletin, 388C, dated 11/2004, to perform an inspection of the Exhaust Valve clearance with the guide. The purpose for the MSB was two fold: to check for not enough clearance or too much clearance between Valve Stem and Valve Guide. Not enough clearance is caused by coking of the Valve Guide due to oil burning and attaching to the wall of the guide. Over time this can cause a condition referred to as "Morning Sickness" - where the Exhaust Valve will tend to stick to the guide during the last engine shutdown and becomes noticeable on the next startup by a rough engine that - after running for a few seconds becomes smooth. (the valve releases from the guide). The other condition is the valve and the guide wear to the point of causing the valve to hit the Valve Seat at an angle that could result in the valve head snapping off due to the valve hitting the seat at an angle and subjecting the valve to stress. Either one of these problems could ruin your whole day.
Lycoming recommends this procedure should be accomplished every 300 hours for helicopter engines and 400 hours for all other engines.
To accomplish this inspection requires a way to measure the valve movement in relation to the guide.
Lycoming recommends purchasing an Adapter with a Dial Indicator at the tune of $3000. plus from Lycoming.
AirWard has developed an Adapter with Dial Indicator plus Valve Stem Extension to accomplish this procedure.
The Kit includes the following:
- Adapter (mounts on Cylinder);
- Dial Indicator;
- Extension (mounts on Valve Stem);
- Bushing (used under Extension);
- Bushing (when checking Intake Valve).
- Allen Wrench;
- Copy of Lycoming MSB 388C Procedure to Determine Exhaust Valve Guide Condition;
- Copy of Lycoming Service Instruction 1425A - Suggested Maintenance Procedures to Reduce the Possibility of Valve Sticking.
The following tools/parts are recommended to complete this Mandatory Service Bulletin:
- 14010 - Rocker Arm Removal Tool;
- AW-Valve Spring Compressor Tool;
- AW-Cylinder Rope;
- AW-Valve Grabber;
- AW-MSB388C Seal/Gasket Kit;
- 4LGR6 Reamer - Adjustable - Intake Valve Guide;
- 4LGR7 Reamer - Adjustable - Exhaust Valve Guide.