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Propeller strap strikes passenger after take off from Canberra

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Propeller strap strikes passenger after take off from Canberra

Old 11th Nov 2022, 05:15
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Originally Posted by lamax View Post
Impossible for a person to hold prop stationary once condition lever moved out of feather. Prop brake when operational is fitted to RH power unit only to provide bleed air during turnrounds.
Hmm, interesting thought, but I think while the prop may rotate out of feather position due to oil flow, without it turning it will not reach bottom governing RPM so no fuel or Ng increase will occur. So the force driving the propeller should not increase until BG RPM is reached. In any case I would think most likely the propstrap broke free or was hanging off the prop during start and as has been said flung off during take-off. Two things suprise me in this, one that the prop strap remained on the blade while unfeathered and two, that with such low weight it was able to pierce the shielded part of the fuselage, turns out those rings make decent Ke Penetrators.

It is possible the strap part was detached, but left on the blade and the stair barrier removed thinking they had the whole assembly. That would then make sense that the start encountered no abnormality as it would have wound up freely with the strap just rotating with the blade.
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Old 11th Nov 2022, 05:24
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It's hard to understand how the strap remained on a blade if the a/c was taxied with both engines unfeathered and only detached on the runway after TO power applied.Can't remember prop RPM on taxi but it is significant.
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Old 11th Nov 2022, 08:38
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Originally Posted by TBM-Legend View Post
The God like pilot obviously needs a trip to Specsavers as on his walk around missed the feathered prop
Prop strap is removed after walk around when passenger boarding is complete. Typically removed by ground crew at the last minute and passed to the FA who would then display to flight crew to confirm it has been removed. Obviously a couple of steps missed here.
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Old 11th Nov 2022, 12:58
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So, what I don't get is why they didn't reject the takeoff. Surely that's SOP if you hear a loud bang during the takeoff roll??
Some of the loud bangs that I have heard during the take-off roll include, a galley cart moving, a brewing pot falling out, the toilet seat and lid dropping, the toilet bin falling out and the cockpit door swinging open. Make your own mind up.
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Old 11th Nov 2022, 13:50
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Originally Posted by lamax View Post
Impossible for a person to hold prop stationary once condition lever moved out of feather. Prop brake when operational is fitted to RH power unit only to provide bleed air during turnrounds.
Who said anything about condition lever being out of feather? The CL start detent IS feather. If you actually read my post I wrote, "mechanic could hold the prop stationary while you started it."
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Old 11th Nov 2022, 22:23
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Should have been removed by crew as part of pre flight.. Loganair require a tech log entry to say prop straps are fitted. Crew can remove and sign. We have already been told about it. The penetrating item is the securing pip pin that holds the prop strop to the nacelle. Throw off the strop spinning at 1000 RPM .
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Old 11th Nov 2022, 23:54
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Originally Posted by Propjet88 View Post
From the ATSB Summary https://www.atsb.gov.au/publications...rt/ao-2022-055
Aircraft Details
  • Model SAAB 340B
  • Damage Minor
The ICAO definitions around damage are:
  • Destroyed : The aircraft is not repairable, or, if repairable, the cost of repairs exceeds 50% of the cost of the aircraft when it was new
  • Substantial : Damage or failure that adversely affects the structural strength, performance, or flight characteristics of the aircraft, and which would normally require major repair or replacement of the affected component. Not considered in substantial damage are; engine failure or damage limited to an engine only, bent or dented skin, damage to landing gear (to include wheels and tires), flaps, or wingtips.
  • Minor : Damage that neither destroys the aircraft nor causes substantial damage.
I would have thought that damage involving a hole in the fuselage breaching the pressure cabin would be more likely to be classified "Substantial". If the photographs are genuine, this is a wee bit more than "bent or dented skin".

Fly Safe
PJ88
Indeed, if the photos are genuine the categorisation of the damage as “Minor” is laughable.
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Old 12th Nov 2022, 00:22
  #48 (permalink)  
 
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Impossible for a person to hold prop stationary once condition lever moved out of feather
It is possible to hold the prop steady of any free turbine during start but you get to the point where the torque is such that it becomes more than you can hold, standard practice on the Britannia for reasons I forget, something done on helicopters at times as well.
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Old 12th Nov 2022, 00:27
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Should have been removed by crew as part of pre flight.. Loganair require a tech log entry to say prop straps are fitted. Crew can remove and sign. We have already been told about it. The penetrating item is the securing pip pin that holds the prop strop to the nacelle. Throw off the strop spinning at 1000 RPM .
Not required on Australian SAABs, the prop strap on the left side also holds the stair blocking strap. In all SAAB operations I've been involved with the FO supervised boarding, did the final walk around and then ensured the stair block/prop strap was carried into the cockpit. Never had a prop strap left on in that situation as it's connected to the stairs and it is very obvious. I have heard of Right prop straps being left on during first flight starts from poor walk around. If you are getting ground staff to remove such straps, en-sure tail struts are stowed and fuel doors closed you might be adding an extra level of complication that's just not needed, especially in a rushed turnaround. And like said before basic dressing the props to 45 will ensure the straps are not latched in, so via correct procedure its very easy to avoid. Not sure why you would complicate with extra steps when the FO could close up and personally supervise all the main elements for such a small aircraft. Might be nice to have the FO sitting in the cockpit doing not much for 10 minutes, but seems like wasted time, but hey having extra people running around outside must be fun to watch and you can bitch about pay and conditions for longer.

BTW starting with the prop brake engaged is not done, its started then braked. From what I've heard starting with a prop strap on is very noticeable, so if the start is monitored as it should be you would notice an abnormal temp and then possibly sudden release when the straps let loose. There is no way they got to lineup not noticing a prop was still stationary, that is definitely beyond belief. So the prop must have been rotating from start at some point and come out of feather as normal.

Indeed, if the photos are genuine the categorisation of the damage as “Minor” is laughable.
Not sure it's that much damage, probably not long in the shop and not much cost to fix considering past events.

I'm more amused at why the QLink brake fire is not listed on ATSB yet... Definitely damage to the wheel assembly and legs from the footage, probably more costly than this fix, and something new that warrants the ATSB having a look see as well as having a look over the evacuation procedures. And then the two Jets that descended below minimum altitude in Cairns has missed the news conveniently.

Last edited by 43Inches; 12th Nov 2022 at 01:04.
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Old 12th Nov 2022, 01:21
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Originally Posted by vegassun View Post
Who said anything about condition lever being out of feather? The CL start detent IS feather. If you actually read my post I wrote, "mechanic could hold the prop stationary while you started it."
I've more than 15,000 hours on type, and I would suggest such an action would be both the first and the last time any individual tried that!

By all means though, be my guest.
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Old 12th Nov 2022, 01:22
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Originally Posted by 43Inches View Post

I'm more amused at why the QLink brake fire is not listed on ATSB yet... Definitely damage to the wheel assembly and legs from the footage, probably more costly than this fix, and something new that warrants the ATSB having a look see as well as having a look over the evacuation procedures. And then the two Jets that descended below minimum altitude in Cairns has missed the news conveniently.
Also the Link Saab that went below altitude into Sydney runway 34L the week before……

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Old 12th Nov 2022, 01:22
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Anyone who has spent time at this company in the last few years won’t be surprised that a serious incident has occurred, or more correctly, a serious incident that wasn’t able to be swept under the carpet.
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Old 12th Nov 2022, 01:38
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That is remarkable...

At takeoff, ruffly, the trebuchet would have had about 5500g of radial acceleration going on... and for a 0.4kg mass (what does it weigh? 100gms), the force of the release is around... 22KN... and a velocity of around 330m/sec. That it then popped a hole in the tub is not a surprise. What is a surprise is that it was tenacious enough to hang in there until the takeoff, that takes some amazing schtick.

The imbalance on a prop is surprisingly well damped by Mother Earth when the plane is on the ground, once airborne, all bets are off and the vibration can be spectacular...

Back in about 84, a certain "Brand X" P3C ripped up 2 star pickets, and tore the cuff off a blade which was not noticeable on the ground, but got the total attention of the crew as the gear came off the ground. Was a short flight.
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Old 12th Nov 2022, 02:33
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Originally Posted by brokenagain View Post
Anyone who has spent time at this company in the last few years won’t be surprised that a serious incident has occurred, or more correctly, a serious incident that wasn’t able to be swept under the carpet.
Please enlighten us with the details...
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Old 12th Nov 2022, 03:37
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Originally Posted by vegassun View Post
Who said anything about condition lever being out of feather? The CL start detent IS feather. If you actually read my post I wrote, "mechanic could hold the prop stationary while you started it."
Posted by Krusty I've more than 15,000 hours on type, and I would suggest such an action would be both the first and the last time any individual tried that!
Why would that be the last time some one tried that Krusty? Honest question based on my experience with free turbines.
From what I've heard starting with a prop strap on is very noticeable, so if the start is monitored as it should be you would notice an abnormal temp
My experience with free turbines on helicopters and starting with the rotor held by the aircraft fitted brake or rotor held by an engineer until he no longer could there was no difference in start parameters, in particular EGT.

Particular aircraft have their own idiosyncrasies. The Britannia had a 4,450SHP Proteus free turbine and the prop remained in positive pitch upon shutdown, a prop brake held all props after shutdown and was released prior to start, if there was a wind present from the rear that caused the prop to rotate in the opposite direction it could pick up a considerable rotation speed in the wrong direction which caused considerable bearing load and adverse effects of gas temps over the turbine-before rotating in the intended direction, rather like starting with the wind from the rear on some aircraft. The procedure was to hold a blade between finger and thumb until the turbine began to drive the prop shaft, the blade then moved ever so gently out of the holder's finger/thumb.

Have had to have aircraft repositioned on rare occasions when wind up the rear caused start EGT issues.
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Old 12th Nov 2022, 04:51
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My experience with free turbines on helicopters and starting with the rotor held by the aircraft fitted brake or rotor held by an engineer until he no longer could there was no difference in start parameters, in particular EGT.
Should have been clearer that was in regard to the SAAB, it doesn't take much to stress it out on start, especially the A model engines. Might be that the CT-7 5A/9B have four stage turbines, 2 for each spool, might take more to push past the two aft stages when stationary, could be the engine was just not designed to have stationary Np. The prop brake was an afterthought and not very good from my understanding, heavy, and let go often with a few restrictions on it's use. Tailwind will bother the SAAB, but with the correct procedure you can start without too much difficulty. It is the same core as the T-700 essentially which powers Blackhawks, Apache and other helis, but obvious differences for adaptation to turbo-prop.
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Old 12th Nov 2022, 05:38
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Originally Posted by 43Inches View Post


Not sure it's that much damage, probably not long in the shop and not much cost to fix considering past events.
Where do I find “time in the shop” and “cost of the repair” in the damage categorisation definitions for the purpose of ATSB investigations? If the pictures are genuine, there’s a hole punched through the fuselage … of a pressurised aircraft … that had passengers on board.
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Old 12th Nov 2022, 06:47
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Originally Posted by Lead Balloon View Post
Where do I find “time in the shop” and “cost of the repair” in the damage categorisation definitions for the purpose of ATSB investigations? If the pictures are genuine, there’s a hole punched through the fuselage … of a pressurised aircraft … that had passengers on board.
TBH it has not significantly affected the flight characteristics, structural strength or require major repair. The caveat for engine and skin dents is just for expensive damage in that area that would orherwise fall under the first 3.
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Old 12th Nov 2022, 07:48
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My apologies. I didn’t realise you were an aeronautical engineer with expertise on the type.
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Old 12th Nov 2022, 10:38
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I may not be a smart man, but I'm thinking that a hole through the skin of a pressurised hull is pretty serious, not something you'd bog up.
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