Here's a New One (for me): Unexplained Loss of Power

The other day I was heading for my first instrument landing at night. Daher, flying the VOR-VOR flight plan from Burbank (KBUR) to Redding (KRDD). Everything going just fine, starting descent from ATC-ordered ALT of 32,000. Then, suddenly, I got an oil pressure warning and started to lose power; speed fell until stall.

Today, I checked my Assistance settings: all failures are disabled, unlimited fuel, etc. I have never before had this happen.

What's up?

Thanks, all

Mac6737

So I'm thinking your engine levers were set wrong for descent... maybe you were running a poor mixture setting for that power level. I dunno, but I'd look very closely at the various engine lever settings for the various stages of a flight, where should they be for takeoff, what's the settings for a powered descent or unpowered descent. I mean clearly you got the takeoff climbout correct and maybe the cruise was either good or marginal, but my guess is a poor setting caused the PT-6 to fail.

They are super reliable, but only if you treat them right, and I believe I heard that it can melt themselves fast if you get it really wrong, as it's quite dependent on airflow to keep things at a safe temperature for the whole turbine. That's not a fault of the design, it's just an expected result of operating it poorly and against the operators' instructions... flown properly it's one of the very biggest successes in aviation!

Could also be a couple of other things, maybe related to fuel delivery: maybe fuel tank feed was set to one side and ran dry? That caused a real life fatal accident in my neighborhood back in 2001... just months after 9/11 that small plane crashed into a appartment building (!!!!!). He had set each tank individually for a pre-flight engine run-up, but forgot to put the feed to dual feed setting... so one of the two engines had perhaps 1 minute of fuel left in the fuel lines before it starved and quit. Once that happened, while heavy and slow on takeoff, the remaining engine pulled the plane towards appartments and the rest is tradgedy.

https://www.cbc.ca/news/canada/british-columbia/1-dead-2-injured-after-plane-crashes-into-building-in-richmond-b-c-1.664005

Were your magnetos turned on to provide power, or maybe if they were off, you were running all power on the batteries that eventually ran dry, and then fuel pump stopped...?

Another possibility is fuel icing up... doesn't happen often in real life, but it can pose a serious hazard in rare cases... the fuel chosen maybe doesn't have anti-icing additive, you fly real high in cold season and the turbines get starved of product to burn? This actually happened to a British Airways B-777-200 on short final at Heathrow... amazing everyone walked away, they very nearly didn't.https://en.wikipedia.org/wiki/British_Airways_Flight_38

So I'm thinking your engine levers were set wrong for descent... maybe you were running a poor mixture setting for that power level. I dunno, but I'd look very closely at the various engine lever settings for the various stages of a flight, where should they be for takeoff, what's the settings for a powered descent or unpowered descent. I mean clearly you got the takeoff climbout correct and maybe the cruise was either good or marginal, but my guess is a poor setting caused the PT-6 to fail.

 

They are super reliable, but only if you treat them right, and I believe I heard that it can melt themselves fast if you get it really wrong, as it's quite dependent on airflow to keep things at a safe temperature for the whole turbine. That's not a fault of the design, it's just an expected result of operating it poorly and against the operators' instructions... flown properly it's one of the very biggest successes in aviation!

 

Could also be a couple of other things, maybe related to fuel delivery: maybe fuel tank feed was set to one side and ran dry? That caused a real life fatal accident in my neighborhood back in 2001... just months after 9/11 that small plane crashed into a appartment building (!!!!!). He had set each tank individually for a pre-flight engine run-up, but forgot to put the feed to dual feed setting... so one of the two engines had perhaps 1 minute of fuel left in the fuel lines before it starved and quit. Once that happened, while heavy and slow on takeoff, the remaining engine pulled the plane towards appartments and the rest is tradgedy.

https://www.cbc.ca/news/canada/british-columbia/1-dead-2-injured-after-plane-crashes-into-building-in-richmond-b-c-1.664005

 

Were your magnetos turned on to provide power, or maybe if they were off, you were running all power on the batteries that eventually ran dry, and then fuel pump stopped...?

 

Another possibility is fuel icing up... doesn't happen often in real life, but it can pose a serious hazard in rare cases... the fuel chosen maybe doesn't have anti-icing additive, you fly real high in cold season and the turbines get starved of product to burn? This actually happened to a British Airways B-777-200 on short final at Heathrow... amazing everyone walked away, they very nearly didn't.https://en.wikipedia.org/wiki/British_Airways_Flight_38

This sounds like expert technical advice from a pilot. However, as I said, the only thing amiss on the panel was an oil pressure warning. As to the rest, all my system failure settings (including auto-lean and infinite fuel) are set at "Major Idiot."