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“In 34 years of NTSB investigations they had 2 Cessna 208 engine failures - both due to operational issues such as water in the fuel and the flight conditions.”

Here are some more Pratt Whitney PT-6 engine failures caused by turbine blade failures. Several of them are in the Cessna 208 and several more are in the engine that the 208 uses PT-6A114. Many of them have the same description - loud bang followed by loss of engine power.

1994
http://www.ntsb.gov/aviationquery/brief2.aspx?ev_id=20001206X01229&ntsbno=CHI94LA147&akey=1

“...inspection revealed, “One C.T. blade had fractured through the airfoil in high cycle fatigue. The nature of the origin could not be determined. The remainder of the C.T. blades had fractured in tensile overload.”

2004/2005
http://fsims.faa.gov/PICDetail.aspx?docId=MAY2005

“SUBSEQUENT INSPECTION REVEALED COMPRESSOR TURBINE AND POWER TURBINE BLADE DAMAGE.”

2005/2006
http://fsims.faa.gov/PICDetail.aspx?docId=JUL2006

11/29/2005
“SUBSEQUENT INSPECTION REVEALED FRACTURED POWER TURBINE BLADES.” PT6A66

1/22/06
“PRELIMINARY INVESTIGATION HAS REVEALED TURBINE BLADE DISTRESS.” PT6A114A Cessna 208B

03/02/06
“INSPECTION REVEALED THAT THE COMPRESSOR TURBINE BLADES HAD SUFFERED EXTENSIVE DAMAGE. 12 CT BLADES WERE FOUND DAMAGED TO VARYING DEGREES OF THE BLADE SURFACE MISSING. ANOTHER 12 BLADES EXHIBITED FATIGUE CRACKING EMANATING FROM THE TRAILING EDGE OF THE BLADE.” PT-6T

04/05/06
“SUBSEQUENT INVESTIGATION REVEALED FRACTURED COMPRESSOR TURBINE BLADES.” PT6A34AG

4/7/06
“SUBSEQUENT INSPECTION REVEALED FRACTURED POWER TURBINE BLADES.” PT6A25

4/29/06
“SUBSEQUENT INSPECTION REVEALED DAMAGED POWER TURBINE BLADES.” PT6A67D

05/08/06
“SUBSEQUENT INSPECTION REVEALED DAMAGED POWER TURBINE BLADES.” PT6A67D

5/30/06
“UPON INVESTIGATION BY MAINTENANCE THE RT ENGINE SEEMS TO HAVE SUFFERED A POWER TURBINE BLADE FAILURE.” PT6A67D

5/31/06
“SUBSEQUENT INSPECTION REVEALED FRACTURED POWER TURBINE BLADES” PT6A67D

Also in 2006 (03/05 and 03/09) there were two Cessna 208Bs that suffered sudden engine failure but the cause had not been determined at the time the report was written.

2006/2007
http://fsims.faa.gov/PICDetail.aspx?docId=JUN2007

12/20/2006
“SUBSEQUENT INSPECTION REVEALED FRACTURED POWER TURBINE BLADES.” PT6A27

01/25/07
“THE BLADE WHICH FAILED AT THE FIRTREE SHOWED EVIDENCE OF FATIGUE WITH AN ANOMALY AT THE ORIGIN.” PT6A65B

2009
http://fsims.faa.gov/PICDetail.aspx?docId=JUN2009

4/21/09
“CT BLADE FAILURE” PT6A27

4/29/09
“POWER TURBINE BLADE FAILURE” PT6A114

5/5/09
“A VISUAL INSPECTION OF THE ENGINE REVEALED THAT IT EXPERIENCED AN OVERTEMP CONDITION AND THE TURBINE BLADES WERE MELTED. PARTS OF TURBINE BLADES WERE FOUND ON THE RUNWAY WHERE THE PILOT HAD JUST LANDED.” PT6A114 Cessna 208

2010
http://aviation-safety.net/database/record.php?id=20100905-0

“The accident resulted from the creep rupture of one or more blades of the turbine compressor leading to failure of the engine in flight.” PT6A-114A Cessna 208B

1/20/11
http://fsims.faa.gov/PICDetail.aspx?docId=JUN2011

Catastrophic engine failure on Cessna 208B with PT6A114 engine. Caused not determined at time of report.

Now that is interesting information, one could hardly call the majority of those events catastrophic engine failure - without the turbine blade fractures, the engines would not have 'coughed' and ceased to produce power, the fault in most events was external to the engine. The manufacturer can't be held liable for that, it would appear to be Cessna's problem.

Over and over again...a Cessna drops out of the sky through metal fatigue of the propeller and there's no enquiry? Those aircraft should be grounded until the fault is rectified. If that was a motor vehicle recall notices would have been issued long ago.

The only relevant incidents are with the PT6A-114A. Show me the NTSB reports on engine failures for Cessna 208B’s having a PT6A-114A engine.

I did stipulate at one point, as my source did, that the statistics used were for engine failures of commercial aircraft that were investigated by the NTSB. The reason for that stipulation is that there is a world of difference in the maintenance and repairs by commercial airlines, as opposed to non-commercial aircraft. As in the case where the mechanic put in the wrong part, user error in one case does not explain engine failure in a case where the protocols and recommendations are followed to a T, to protect against lawsuits. Makani Kai says they did their maintenance to HIGHER standards than are required for commercial planes.

Some flying conditions will also wear out parts more quickly, as is alluded to in some of these cases. But Makani Kai just made short passenger flights in good weather at low altitudes, where there wouldn’t be icing or some of the aircraft stressors that come from longer flights. That’s my understanding; if somebody knows otherwise they can point it out to me.