C208 Crash Hawaii

[Sarcs]

Obviously too early to say whether sulphidation was a factor causal to this accident but it is a factor the NTSB will surely explore given the environment the aircraft was operating in.

Here is the incident report from the 1998 VH-URT engine failure for those interested: Cessna Aircraft Company 208B, VH-URT

From the Safety Action section it can be seen that the URT incident was instrumental to CAsA issuing AD/PT6A/28:

Following the incident, the Civil Aviation Safety Authority issued the following directions to the operator:

1. Conduct daily water washing of the compressor and compressor turbine, after the last flight of the day when operating in a salt laden environment,
2. Conduct engine condition trend monitoring (ECTM) in accordance with the procedures detailed in CASA Airworthiness Advisory Circular 6-29 Amdt-1, and
3. Conduct boroscope inspections of the compressor turbine at intervals not to exceed 110 hours time in service, or alternatively conduct datailed hot end inspections at intervals not exceeding 750 hours time-in-service.

In addition to these directions, CASA issued Airworthiness Directive AD/PT6A/28 applicable to all PT6A series engines installed in single-engine aircraft. This airworthiness directive detailed the requirements listed above as well as requiring all operators to carry out a visual inspection of the compressor turbine blades for evidence of sulphidation, and to continue to carry out engine compressor turbine washing in accordance with the procedures detailed in the applicable Pratt and Whitney Canada maintenance manual.

CASA also published an article in the November 1998 issue of the CASA magazine Flight Safety Australia, which outlined the circumstances of the incident, and explained sulphidation, its causes, and preventative measures.

And here is a link to the Flight Safety November 1998 story mentioned (pg 7): Engine Trouble

However there is a factor in the Uzu incident that both FF & the bureau failed to pick up on, perhaps best described in a Torres post from a closed thread in 2003 titled CASA in the news Important Urgent - Insight on SBS on Thursday night
... :

Ah, yes, our Caravan engine failure and the Director of CASA flying the aircraft on another occasion.

I'm actually please you raised those points:

1 The PT6A-114A engine was being maintained totally in accordance with Pratt & Whitneys requirements to use "pottable water" for compressor washes. It wasn't until a subsequent laboratory test of the Horn Island water supply that it was found to contain totally unacceptable levels of heavy metals and silica. Yes, I'm guilty. But didn't the pilot do a great job landing at Badu! We had the first beach side Caravan park in the Torres Strait!

& at post #38:

But the cause of the problem was mineral build up on the CT Blades from using Horn Island tap water, knowing the island was heavily mineralised (there is a gold mine and significant mineral deposits on the island) we didn't "tweak" to the fact the treated water may not be "potable". (I don't recall exact details of the analysis, but do recall the silica content was 18 times the acceptable level.)

On the Creamy & Torres by-play, the DAS/CEO issues & the Fort Fumble critique...well some things never change..

But I digress back to the thread...