Honeywell has recently issued a few service bulletins of interest for MU2 owners and operators. The first one to note is Service Bulletin TPE331-72-2208. This is a Category 2 service bulletin which addresses a substantial improvement to reliability. 72-2208 applies to all second stage compressor impellers P/N 893482-1 through -5 and 3107056-1,-2 so it will likely affect all MU2 engines currently being operated.
This service bulletin installs a new impeller P/N 3108387-1 or 3107167-1 with better design qualities to prevent possible cracking at the curvic tooth area. Removed impellers that are inspected by Honeywell and found to be serviceable may undergo a rework and re-identification process and be re-installed with an imposed cycle limit established for the part.
Current pricing for the new part is $12,067.00 and there is no program pricing or MSP coverage at this time. Honeywell recommends compliance with 72-2208 at next access to the 2nd impeller, but no later than next overhaul or CAM compressor inspection.
The second service bulletin consists of three separate bulletins addressing different engine models and pertains to the Combustion Chamber Assembly or Plenum as many people know it. All three service bulletins are Category 1 service bulletins which addresses a safety issue.
Service Bulletin TPE331-72-2218 applies to all 331-10 models currently installed on MU2 aircraft, TPE331-72-2233 applies to 331-1 engines for the “F” and “G” model operators and TPE331-72-2234 covers the 331-5/-6 engines for the various MU2 models utilizing these particular engines.
All of these service bulletins address installing a more robust Combustion Chamber P/N 70100072-X which is not prone to fatigue cracking at the weld joints. Currently the cost of the new plenum is $17,635.00 and there is no program pricing, however MSP coverage applies.
Honeywell recommends that these service bulletins be accomplished at the next Combustion Chamber removal from the engine, but no later than next Hot Section Inspection.