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Safety around propellers

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Safety around propellers

Old 1st Jan 2019, 21:18
  #101 (permalink)  
 
Join Date: Dec 2002
Location: Melbourne Australia
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Only slightly off topic:

I am becoming increasingly concerned at the number of "professional" pilots I see walking through the prop arcs. Any links to decent educative material relevant to the dangers of this activity gratefully received.

MJG
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Old 3rd Jan 2019, 05:05
  #102 (permalink)  
 
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MJG. The only education I got was from crusty old FSGTs at Pt Cook. If you didn't walk around the prop on your walkaround they would belt your helmet far harder than any QFI. And then occasionally, you would hear a cough and see a prop turnover with noone in the cockpit.....
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Old 3rd Jan 2019, 05:31
  #103 (permalink)  
 
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Originally Posted by Fostex View Post
Swapping out students with a running engine, while safe if performed correctly (and depending on aircraft type), is not really the best practice when teaching students. It needs to be emphasised to anyone new to flying that being a pilot is not just about handling the aircraft in flight but rather all aspects of safety around the aircraft when airside. That includes the safe startup and shutdown of the engine as well as the use of mags, throttle, mixture and pitch to manage the prop. By simply turning up to a running aircraft and jumping in the student is missing a lot of the learning experience. Not a good idea in my opinion.
Exactly. That was my 'other' concern with the practice. You would loose out on all the essential stuff associated with preflighting, pre-start checks, comms with ground, shut down checks (do they also skip power checks?) and I worry that would change the way a student learns to take responsibility for the whole operation.

Last edited by double_barrel; 3rd Jan 2019 at 06:34.
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Old 3rd Jan 2019, 20:13
  #104 (permalink)  
 
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Untill I read the above discussion before Christmas I 'thought' I was careful when ground handling handling my 80 h.p. Rotax powered Rans at my strip.
It set me thinking on how I might operate more safely and wrote the following proto checklist; it's initially for discussion here - bearing in mind it's one man alone at the strip and not so complicated please that one abandons using any checks.

Precaution Treat the Propeller as Always LIVE - A handling regime.

With hot or cold engine even with both ignition 'kill' switches turned to off, turning the propeller could cause it to suddenly fire either forwards or in reverse due to a hot spot or a single 'kill' switch wiring could have an intermittent open circuit.
Rotax never-the-less require the propeller of a cold engine to be rotated forwards by hand many turns to blow crankcase oil back up into the tank to check oil level, & to ascertain there is no hydraulic lock.
Precautions :-
a) Always chock the main wheels.
b) Tie back stick.
c) Throttle closed.
d) Both Ignition switches OFF.
e) Stand on firm ground and rotate the propeller keeping one's arms, body and clothing away from its arc.
f) Pulling the a/c out of its hangar holding the propeller roots reqires equal care.
g) Once in the cockpit ready for engine start, shout "CLEAR PROP" and wait at least 7 to 10 seconds for it to register to anyone unseen outside before operating the starter..
If possible avoid post flight prop/compression checking, it is even more risky.
But, with care as above, the propeller might need turning to re-position an upwards pointing blade to clear the hangar entrance beam for pushing back inside.

Could readers kindly comment ?
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Old 3rd Jan 2019, 20:37
  #105 (permalink)  
 
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Originally Posted by mikehallam View Post
Untill I read the above discussion before Christmas I 'thought' I was careful when ground handling handling my 80 h.p. Rotax powered Rans at my strip.
It set me thinking on how I might operate more safely and wrote the following proto checklist; it's initially for discussion here - bearing in mind it's one man alone at the strip and not so complicated please that one abandons using any checks.

Precaution Treat the Propeller as Always LIVE - A handling regime.

With hot or cold engine even with both ignition 'kill' switches turned to off, turning the propeller could cause it to suddenly fire either forwards or in reverse due to a hot spot or a single 'kill' switch wiring could have an intermittent open circuit.
Rotax never-the-less require the propeller of a cold engine to be rotated forwards by hand many turns to blow crankcase oil back up into the tank to check oil level, & to ascertain there is no hydraulic lock.
Precautions :-
a) Always chock the main wheels.
b) Tie back stick.
c) Throttle closed.
d) Both Ignition switches OFF.
e) Stand on firm ground and rotate the propeller keeping one's arms, body and clothing away from its arc.
f) Pulling the a/c out of its hangar holding the propeller roots reqires equal care.
g) Once in the cockpit ready for engine start, shout "CLEAR PROP" and wait at least 7 to 10 seconds for it to register to anyone unseen outside before operating the starter..
If possible avoid post flight prop/compression checking, it is even more risky.
But, with care as above, the propeller might need turning to re-position an upwards pointing blade to clear the hangar entrance beam for pushing back inside.

Could readers kindly comment ?
Not strictly Ground Handling, but regular Mag Checks will reduce the risk of a faulty mag switch or wiring creeping up on you!
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Old 3rd Jan 2019, 20:56
  #106 (permalink)  
 
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My 2c - I am not overly familiar with Rotaxes but understand many are shut down by turning mags off rather than cutting mixture(?). If so, in that case you would be likely to detect a live mag on shutdown because the engine would keep running so you would know if there was an issue there. Effectively you are forced to do a live mag check every shutdown.

Whilst not impossible, I am guessing it would be pretty unlikely for a mag to cut OK on shutdown and then go live afterwards.

Also for the prop to fire you need a suitable fuel mixture available in at least one cylinder - I would assume that would be unlikely if the aircraft hadn't been recently running. If a warm engine though... I would be more cautious.

I think if you are doing the oil pull-through process you require, on a cold engine that you personally have shut down from the last flight, handling the prop would be unlikely to be a high risk.

Doesn't mean you treat props casually - ie don't stand where you could be struck if moving it.

(NB If hand swinging to start, rather than to check oil or adjust blade position, that should involve more care).

That is me personally. You need to make your own decisions though. Other's may have differing opinions.
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Old 3rd Jan 2019, 21:15
  #107 (permalink)  
 
Join Date: Dec 2005
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Twice thanks,

And yes i) I've owned it O.K. thus for 10 years
and
ii) Post flight switch off is done each ignition in turn - no weak cut offwith the Bing carb's.

Last edited by mikehallam; 3rd Jan 2019 at 21:16. Reason: sp.
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Old 24th Jan 2019, 21:22
  #108 (permalink)  
 
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"Whilst not impossible, I am guessing it would be pretty unlikely for a mag to cut OK on shutdown and then go live afterwards."
As mag switches earth the mags, any break would make the mag live.
Vehicle ignition switches fail dead - and the engine stops.
Mag switches fail live, so the engine doesn't stop, and you keep flying, still with 2 mags.
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Old 30th Jan 2019, 10:24
  #109 (permalink)  
 
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Engines running crew changes were often done on the RAF C130K fleet. The Air Loadmaster (ALM) would exit first from the crew entrance door and screen the engines off with his very long intercomm lead providing a 'fence' to remind crews not to turn into the propeller arcs. As far as I know without any incidents occurring. The ALM would renter the aircraft last.

I remember, around about 1970, a Britannia aircraft, on engine start at night, one of the start up crew walked in to a propeller with fatal results. (It was necessary for a start crew member to ensure that the hold the propeller during engine start to ensure that it was not turning in the wrong direction at the beginning of the start sequence, so they would always be very close to the propellers). I think that the Board of Inquiry concluded that the bright apron lighting caused the propeller to appear to be stationary due to the stroboscopic effect.

From Wikipedia:
The stroboscopic effect is a visual phenomenon caused by aliasing that occurs when continuous motion is represented by a series of short or instantaneous samples. It occurs when the view of a moving object is represented by a series of short samples as distinct from a continuous view, and the moving object is in rotational or other cyclic motion at a rate close to the sampling rate. It also accounts for the "wagon-wheel effect", so-called because in video, spoked wheels on horse-drawn wagons sometimes appear to be turning backwards.

Last edited by DeanoP; 30th Jan 2019 at 10:27. Reason: spelling
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Old 30th Jan 2019, 19:36
  #110 (permalink)  
 
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Originally Posted by Maoraigh1 View Post
"Whilst not impossible, I am guessing it would be pretty unlikely for a mag to cut OK on shutdown and then go live afterwards."
As mag switches earth the mags, any break would make the mag live.
Vehicle ignition switches fail dead - and the engine stops.
Mag switches fail live, so the engine doesn't stop, and you keep flying, still with 2 mags.
Exactly.

I would suspect switches more likely to fail with the engine running (due sustained vibration). Why a mag check on shutdown important.
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Old 3rd Feb 2019, 11:46
  #111 (permalink)  
 
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Small beer, but that is where Rotax have an edge as every shut down requires the "kill" switches to earth the two ignitions.
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Old 3rd Feb 2019, 16:29
  #112 (permalink)  
 
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Surely it is normal shut down procedure to check each mag for cut prior to pulling the mixture? This both identifies a grounding issue and will also show any previously unknown mag issue which may have developed during flight.
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Old 6th Feb 2019, 07:31
  #113 (permalink)  
 
Join Date: Nov 2013
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live changeovers

Originally Posted by Homsap View Post
If someone disembarks or boards on a Cessna the door and wing strut generally prevents someone walking into a live prop. like wise on Pipers the door again prevents someone walking into the prop.

The problem is with aircraft with sliding canopies such as the Bulldog, Grob115, Robin DR200, DR400, the poblem is boarding with the engine running, that you could slip on the wing and fall of the front of the wing, likewise upon disembarking an aircraft the danger is 'going the wrong way' and jumping of the leading edge into the propellor. I was warned of this when I started flying DR200s, as I was told this happened with fatal results at Sywell in the eventies and eighties.

During my career on several occasions I have seen people hand swinging aircraft, when there is no occupant in the aircaft, utter maddness!

Historically, the RAF did live changeover of air cadets on on the DHC Chipmunks as the had explosive cartriges and their were only six, but the air cadet was always ecort. It would be interesting to know what happens on the RAF grob? In the instructing world instructors have in the past asked student pilots to start the engine and then board.

As most modern aircraft have electric starters, there is no need for anyone to board or disembark with a live engine. On aircraft where handswing takes, the person who is handswinging and the occupant should be sufficiently qualified, trained and pre=briefed not to walk into the prop,
I was one of those cadets, at 15 I would walk up the wing and stand by the pilot in the front seat and get the cadet out one side and the next one in the other side with the engine idling. Then strap them in and exit back down the wing rearwards. We had very strict procedures instilled in us including never approaching a prop, even if the engine was off. I can't imagine the "elfansafety" letting kids do that now.

Fast forward 10 years and I'm stood under the nose wheel of a 747 in the middle of a taxiway, tug has removed the towbar and I'm waiting, hopefully, for the "OK, thanks, see you next time" on the intercom. It's a lonely place and with zero training, except cadet experience around live aircraft.
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Old 17th Feb 2019, 18:52
  #114 (permalink)  
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I was taught never to handle a prop unless you knew the mag switches were off. That was enough for me so never ever touched one. What amazed me though on the Hastings and Lancaster was the flight eng aligning all the props the same way.

It looked neat and as the flt eng he probably knew the mags were off.

I think on the Shack someone managed to pass through both prop arcs.
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Old 25th Feb 2019, 23:09
  #115 (permalink)  
 
Join Date: Jan 2019
Location: Bristol
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Tail rotors also bite

In just over 12 years at first line on helicoptors I saw a number of close calls with tail rotors, fortunately only had one myself due to a Wesex pilot turning before the marshaller gave the signal during a 3 ship 'formation' taxi landing and shut down. At 6'2" it was frighteningly close to my head. Towards the end of my helicoptor first line experience I worked on flat tops in the dark. You know that the tail rotor is there, you can hear it and feel the turbulence from it, you know it is at head hight but can't see a thing. When attaching the tail lashings to a running helicopter the drill is to monkey walk in, knees bent head down, attach the lashing to the ac lashing point and crawl out to the elephant's foot lashing point. Used to scare the last meal I ate out of me every time. How more fatalities don't occur is a mystery and a credit to the training and professionalism of those who operate as ground crew on embarked helicoptors. There is nowhere as dark as a flight deck out in the ocean under 'darkened ship' conditions. The most effecient killing machine known to man has to be the tail rotor of a helicopter, the final twist being a helicoptor tail rotor under 'darkened ship' conditions in a heavy sea. Having said that they tend not to start of their own accord like props on piston engined ac can and do.
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