Emir wrote:
As the author mentioned in video, it’s an engine with unknown history, so anything could happen in the past to these blades, exposing them to temperatures and strain beyond the limitations causing the effects of fatigue to be more prominent than expected. One broken blade can cause (and probably caused) a havoc in compressor causing engine catastrophic failure.
@Emir, my understanding was that a manufacturer would have to prove that in the worst case scenario (a debris with the highest possible energy) nothing leaves the engine case. Of course, if the engine case wasn’t maintained as well, then, yes, all bets are off; although, I wouldn’t walk near such an engine when it is running. :)
arj1 wrote:
@Emir, my understanding was that a manufacturer would have to prove that in the worst case scenario (a debris with the highest possible energy) nothing leaves the engine case. Of course, if the engine case wasn’t maintained as well, then, yes, all bets are off; although, I wouldn’t walk near such an engine when it is running. :)
As I understood from video, it was second stage of axial compressor where it probably started, so it seems that the failure wasn’t caused by external debris but internal failure. I don’t know what has to be demonstrated for such failure.
Depite the engine issue, it’s still a story to go engine out and make a safe landing.
In a Cub over flat farmland not a big story maybe, but in a high performance single that lands around 120-130 kts making the field is a great outcome and some good flying.
I know we all practise engine-out but it’s commonly to a best-choice field not a specific hard runway from flight levels.
I have in the past considered whether I’d be capable of exactly this from 18k and I hope I would be, but a good outcome I think.
If I didn’t feel so uncomfortable doing idle from 4k in a large Turbo Conti, I’d practice this a couple of time a year.
Emir wrote:
As I understood from video, it was second stage of axial compressor where it probably started, so it seems that the failure wasn’t caused by external debris but internal failure. I don’t know what has to be demonstrated for such failure.
@Emir, for that precise case (a blade detaches due to defect/fatigue etc) you have to show that you have no penetration of the engine case by the debris.
It would be interesting to see the results of the investigation…
GA_Pete wrote:
Depite the engine issue, it’s still a story to go engine out and make a safe landing.
In a Cub over flat farmland not a big story maybe, but in a high performance single that lands around 120-130 kts making the field is a great outcome and some good flying.
I know we all practise engine-out but it’s commonly to a best-choice field not a specific hard runway from flight levels.
I have in the past considered whether I’d be capable of exactly this from 18k and I hope I would be, but a good outcome I think.
If I didn’t feel so uncomfortable doing idle from 4k in a large Turbo Conti, I’d practice this a couple of time a year.
True that it’s probably a tricky plane to land in those conditions, but I feel like with any plane having plenty of altitude and a proper runway within reach is actually the situation that I would choose if I had to.
His main issue having to lose so much altitude was the risk for engine fire over time, as there was oil everywhere and exposed wire.
Sounds like there is a lesseon to learn here. The normal procedure after a hot start would have been to extract 2 blades and send them out for testing. Probably the test would have shown no real issues, purchase 2 new blades and continue flying. Those guys wanted to do it “perfect”, spent probably half a million dollars on an overhauled or new engine, installed a loaner engine with completely unknown history, the turbine equivalent of a 100.000km beat up rental car and it blew up shortly after installation. Maybe someboy had a worse hot start in it before and did not report? Maybe it was dropped during shipping etc? Some components might have decades of service life in them and be reinstalled many times at overhauls (with inspection). They also did a lot of firewall forward work which comes at some risk. Maybe some washer was forgotton somewhere etc.? So the bottom line is this is a little like surgery. Definitely do it if you have to but consider before every step the risks and benefits. Simply doing a lot of invasive work to be “safe” often results in the opposite. Lets cut that 80 year old person open and look inside, maybe we find something wrong. Hey wait the person died because of an unfortunate infection sustained during surgery…
Sebastian_G wrote:
installed a loaner engine with completely unknown history,
If I understood the video right, he bought this used engine from P&W. They only had 5 hours on it in his aircraft, but as you wrote, it was an old engine.
If he had experienced a fire, it would have been a horrible day for him and his sidekick. While it sounds easy to land an aircraft on a long runway with about 20k feet to get down, many good pilots have failed.
Not sure if it was just for the show, but I was surprised he seemed surprised to have all the engine data. I would have expected he’d be looking at this after each flight. In fact, if I was P&W, I’d be working to get this data after each flight from every engine out there.
For better understanding, this is a dual-shaft engine with a “power turbine”, connected to the gearbox and driving the prop, and a “compressor turbine”, driving the..er, compressor. In the video the former turbine is called PT and the latter CT .
Sebastian_G wrote:
Simply doing a lot of invasive work to be “safe” often results in the opposite. Lets cut that 80 year old person open and look inside, maybe we find something wrong. Hey wait the person died because of an unfortunate infection sustained during surgery…
During WWII, the RAF dramatically improved dispatch rate by increasing inspection intervals…
Antonio wrote:
In the video the former turbine is called PT and the latter CT .
Did he tell in one point in the video that missing blade is probably from PT?
