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-   -   Safety around propellers (https://www.pprune.org/accidents-close-calls/562596-safety-around-propellers.html)

mustafagander 13th Nov 2015 10:33

It was SOP on Britannias as I recall it. When I were but a lad my crew used to service the CP Brits transiting SYD and that was one of my jobs, hold the prop until it pulled away from my hands in the correct direction of rotation.

Always had quite an audience!! :ok:

Capot 14th Nov 2015 08:21


During the pre-flight and when pushing or pulling a plane back into the hangar
Once again, as we dinosaurs know well, this is fine just so long as you know that turning a prop through a compression can cause a hot engine to fire with the mags switched off.

I shudder when I see students assiduously doing their pre-flight and grabbing the prop to give it a turn on an aircraft that was landed and vacated 15 minutes before by the previous user, and I look away when I see people grabbing a hot prop to move an aircraft that landed 5 minutes before. Trust me; it happens.

It's Darwin Award territory.

Gertrude the Wombat 14th Nov 2015 10:24


I shudder when I see students assiduously doing their pre-flight and grabbing the prop
My passenger briefing includes "Stay away from props, especially ones that aren't going round. It only takes three things to go wrong at once for a prop to burst spontaneously into life, and we like better odds than that around little aeroplanes. So, no selfies draped across the prop please."

Thruster763 14th Nov 2015 18:12

On holding props during compressor washes http://www.pprune.org/accidents-clos...ml#post9100126

This was standard practice on PT6's As a free turbine engine its easy at motoring speed. Don't try it with a TPE-331 though.

DownWest 16th Nov 2015 06:19

Props and chocs
 
We were doing engine runs on a rebuilt Stamp SV4 fitted with the Renault engine. This had an air starter with a little knob on the panel that you pulled out. This in turn had a little spring loaded lock, so both hands were required to operate it.
One of our junior mechs was in the seat and got ready to start, while I put the chocks in front of the wheels. With not much pressure in the cylinder, the knob needed to be pulled out over an inch before anything happened, but I had been running the engine just before, so the cylinder was fully charged. As soon as he moved the knob the engine turned, and fired, as he had the switches on.....The blade went through the hair on the back of my head (had more then..) Choice words followed about not taking anything for granted, and sticking to the rules.
DW

Geosync 10th Dec 2015 18:56

When I was a mechanic we would do engine runs in the middle of the night on beater Cessnas, huge torch in hand, checking for oil leaks after maintenance. I would ALWAYS have one hand on a strut, and if I couldn't see the front of the engine using that method then so be it. The scarest part was adjusting the carb idle screw while that puppy was running.

One time at a remote airfield I had a dead battery in a Cessna 150. I was deciding how I would hand prop it without anybody around to hold brakes when an old grizzled IA drives up out of nowhere and offered to help. He told me to get inside and hold the brakes while he tried to hand prop it. After a while he was unsuccessful, so he pulled up his car and jumped the battery.

But in order to get the battery box lid back on, this old grizzled IA withstood the mighty wind forces the O-200 was producing and stuck his hands in the tiny access panel to pin it in. The angle was screwy, so he was gyrating all over to get it in, bringing parts of his body within inches of the blade. I was holding the brakes like mad. He eventually was successful, gave me a slight nod, jumped in his car and drove away, leaving me alone with the weeds and coyotes to contemplate life.

LJP 14th Dec 2015 00:12

compressor wash
 
Thruster763 obviously paid no attention to maintenance manuals. Cowboy attitude. MM specfically states not to hold prop during compressor wash on PT6. On 331, no advantage derived from compressor wash.

Wunwing 17th May 2016 02:40

I was told when I started on museum aircraft that there was a problem with the Wright powered aircraft, where if a relay stuck on, with GPU applied the starter would turn and as a result the prop would turn.

One day I powered up our Neptune and as the plug went in, the starter engaged. Fortunately on the L/H side where the GPU plug is,so it was obvious immediately.

The other Wright aircraft in our fleet needed power to be selected on the F/Es panel but it was possible with that as well. It took me quite a bit of arguing to convince the others on site that this was a real threat.

Wunwing

Tankertrashnav 18th May 2016 10:53

When I was at Seletar in the 60s we had a squadron of Beverleys. The prop clearance on this aircraft was about 7 feet and although it was forbidden some of the blokes used to take a short cut under the props. This was ok until one of them got a posting across to the Argosy squadron at Changi and tried the same trick there, with predictable fatal results.

TomU 18th May 2016 11:37

I stopped someone walking into a prop.
Arriving a Britannia, I was on the headset as chock man installed the nose chocks, then proceeded towards the MLG to put the chocks. Only problem was that spinning prop was between him and MLG. He was head down with ear muffs on, dragging the chocks on ropes.
He didn't hear my shouting - I managed to rugby tackle him just ahead of the prop.
Far as I remember (it was 40 years ago) he just cursed me for hurting his knee.

TomU 18th May 2016 11:40


Originally Posted by mustafagander (Post 9179541)
It was SOP on Britannias as I recall it. When I were but a lad my crew used to service the CP Brits transiting SYD and that was one of my jobs, hold the prop until it pulled away from my hands in the correct direction of rotation.

Always had quite an audience!! :ok:

Indeed, I remember that. The Brit did not like to start with the prop reverse rotating, so we needed to hold it during start. We had competitions to see who could hold the longest! Silly really, I wonder how we survived it.

India Four Two 20th May 2016 21:10

A further point about the dangers of a live prop.

After shutting down our gliding club's C-182, we always put the keys on top of the glare shield so that someone outside can see them.

However, that is not a guarantee that the engine can't start. Apart from the obvious issue of a potentially broken ground wire, it is also possible with some keys, to remove them from the ignition switch, when it is set to Both.

I have personally had that happen to me with a PA-28 and I've heard that it is fairly common.

Gertrude the Wombat 20th May 2016 21:31

How to get onto a floatplane when parked nose in to a jetty: hold on to the propeller as you step onto the front of the float (there's nothing else you can reach). Never entirely happy with that sort of thing.

SpannerInTheWerks 30th May 2016 20:55

1. Always treat the propeller as being live

2. Never touch a propeller unless you have too

3. pass the message on ... !

I seem to remember a loader was killed at Aldergrove in the mid 90s when he walked into a HS748 prop?

squidie 2nd Jun 2016 21:47

When I was training we were instructed to walk out to the A/C and perform our pre-flight checks and then start the engine and waiting for the instructor to board before calling for taxy. It used to worry me everytime when I watched the instructor climb onto the wing of the HR200 and then open the canopy and climb in. Itís so easy to slip and fall over the leading edge and within the prop arc and Iím surprised an issue hadnít already pccured to that day.


Eventually (still as a student and after) I decided to simply wait for the instructor before powering up off my own occurred.

gruntie 12th Aug 2016 07:25


1. Always treat the propeller as being live
Drummed into me while I was in the CCF by a serving RAF officer several decades ago.

A couple of decades later I was watching the Italian AF giving a demonstration of mountain rescue at a ski resort, using a large helicopter. It was sitting at the bottom of the pistes rotors running, when for some reason the co-pilot got out and walked round the back. He slipped on the snow and fell into the tail rotor. 2 stretcher bearers ran over from a parked ambulance: when they reached the scene they just stopped running.
A couple of hours later, having tidied everything up, the helicopter started up and flew away. Without any sort of inspection.

pithblot 30th Dec 2016 12:51

On another thread. A cautionary tale from Dunnunda.


Re my previous post.
One of the scars came from an upside down engine, a Queen 30 as fitted to the DH Heron.
I was lining up the props after a flight, asked the PIC if the mags were off and received an affirmative.
Lined up #1 and moved on to #2 which fired up with hardly any movement of the prop by me.
The prop threw me into the fuselage side and I fell back on to the ground just in front of the rotating prop. The aircraft was inching toward me so I rolled out of the way pronto.
I then ran around the wing up the stairs into the aircraft and found the mags to all four engine in the on position. I shut #2 down and switched off the rest.
Walking down the cabin I saw blood all over the floor, I was wearing a raincoat and the sleeve was a bit over long and covering my left hand. I shoved my hand out of the sleeve to find a V between my index finger and the next one along. Could have held a real big cigar and put Winston Churchills V to shame. The prop must have done this whilst I was performing my aerobatic display.
Anyway I grabbed a stray tarmac terrier to run me into hospital where they spent some time reducing the V to v or maybe u. Good job too though the left arm still aches on a cold day all these years later.
I had a massive bruise on my upper arm which could have only come from the prop launching me into the fuse.
Lucky no doubt. Whilst I was cautious around props before this I have treated them like big black snakes ever since. With an excess of caution.
SD

mikemmb 4th Jan 2017 10:47

Please DO NOT put all your faith in the Mag Switches being OFF.

Decades ago I spent many years as ground crew in the RAF on all sorts of propellor aircraft.
One of the tasks each morning was to turn the engines over using the prop to check for oil leaking into the cylinders (if it did the resulting hydraulic effect on startup could blow the cylinder head off).
We clearly always checked that the Mag Switches were OFF, but still had a fair few engines burst into life in the hanger........certainly catches your attention!

The cause was faulty Mag Switches or associated wiring.

Magneto switch circuitry is different to most other electrical stuff in that the electrical circuit has to be in perfect condition and the switches closed (ie technically "ON") in order to disable the Magneto.

SO IT IS NOT FAIL SAFE - if anything is broken or damaged THE MAG IS ON.

.............Never walk through the arc of a propellor, let alone touch it.

If you do have to turn a prop over, always assume its going to fire and move away from its arc.

Big Pistons Forever 5th Jan 2017 02:31


However, that is not a guarantee that the engine can't start. Apart from the obvious issue of a potentially broken ground wire, it is also possible with some keys, to remove them from the ignition switch, when it is set to Both.
If this happens then the mag switch is US and the aircraft must be grounded until it is fixed. All of the standard light airplane mag switches are specifically designed so that you can only remove the key when the switch is in the off position.

I check for this at the end of every flight by giving the key a little tug at each mag position as I cycle it to off. I have found a few bad switches over the years, all in high time trainers where the switch is just worn out. My guess is in all cases the switches had been like that for awhile but nobody had paid any attention to what they were doing when they shut down :ugh:

Lou Scannon 5th Jan 2017 16:15

When a student on No 16 Vampire/Varsity course at Oakington in the 60's I was told about the "civvy" who, in WW2 and before first light, cycled to work round the perimeter track.

They were equipped with Stirling bombers with their extended undercarriage legs that ensured the four engines had plenty of clearance under them. Knowing this he would remain on the taxyway rather than take to the grass to pass them.

Sadly they re-equipped almost overnight with Halifaxes and he still took his usual short cut..... but through the props rather than under them.


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