March 10, 2026
During the initial climb, the engine experienced a partial loss of power. The pilot performed a precautionary landing on a taxiway, during which the airplane departed the paved surface and the nosegear collapsed.
Postaccident examination of the engine turbocharger revealed reddish-white discoloration of the turbine wheel, which suggested excessive engine exhaust gas temperature (EGT). Likewise, discoloration observed on the turbine end shaft journal was consistent with high temperature. The combination of high exhaust temperature and the rotational speed of the turbine wheel likely caused the blade material to creep and the wheel diameter to increase until the blade tips rubbed against the turbine housing. This eventually caused blade tip failures, which resulted in a rotating imbalance. It is likely that the combination of wheel rubbing and imbalance caused the turbocharger to slow or stop, which in turn resulted in the loss of engine power.
But why excessive EGT? Can turbocharged engines be run LOP? Should they? So many questions!
Per the operator report linked in the docket it looks like this airplane was powered by a Mazda 20B which would have had much higher EGT’s than a reciprocating engine. It looks like coupling a rotary engine with the turbocharger off of a Navajo and operating it in Arizona may have caused the high EGT which caused the plastic deformation of the interior turbocharger parts.
A statement in the accident report itself saying that rotary engines have a much higher EGT than a piston engine would have made connecting the dots a bit easier, instead this nugget of information was buried in the Hartzell report on the turbocharger.
Back in my days at Garrett Airesearch in the early 1980’s, there was a heavy emphasis on thermodynamic and systems integration. Sounds like it might have come in handy here….