914 turbo overboost/crankshaft distortion symptoms?

Hello Tom

The overboost will be recorded in the TCU.  The data can be seen on a BUDs readout using a simple serial cable to connect to your laptop.  The BUDs software will interface with the TCU and you do not need a special DONGLE to read it.  The connection and way to download the logs is found in the latest maintenance manual heavy, MMH, online from Rotax-Owner or Flyrotax websites.

Generally speaking an overboost will not distort the crankshaft.  it normally takes a high pressure, say in excess of 50 inch HG, for a prolonged time to twist the crank pins.  Repeated overshoot of the pressure over time may twist it.  The amount of pressure and the time for each event will be found in the log files.  

For a twisted crank the most common finding is the engine starts to turn over very hard, excessive drag.  This is because the certener journal will be misaligned with one of the outside pins. This can be checked by a crankshaft distortion test, you can find this test inside the MML.  Persons who have the iRMT Maintenance rating are shown how to do this.  It will confirm if the crank has failed and needs replacement. 

Cheers

Opps, distortion check in in MMH, not MML.  it is 3 pages, I include page 1 for reference.  The other is from the MML on the hard to turn over, if it is hard to turn over then you have to do the distortion check.

Cheers