Ignition Key Warning.....

Cruzinchris

Cruzinchris

Pre-takeoff checklist
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Cruzinchris
An article appeared on Kathryn's Report's about someone killed when the engine fired while he was doing a pre-flight inspection. The throttle was off, mixture idle cutoff and the ignition key was in his pocket.
http://www.kathrynsreport.com/2019/07/propeller-contact-with-person-cessna.html

Turns out the key could be removed while in any position in addition to OFF. Apparently it was still R.

Some time ago I noticed that the key on my Beechcraft Sport could be removed in any position. My plane came with several keys. The one I was using was worn pretty bad. Using another key "fixed" the problem.

Everyone should check this on their plane.
 
I recently replaced the ignition switch and a p-lead for that very same problem. You could start the plane with the switch in the off position and the key in your pocket. And you could take the key out and the plane would continue to run.
 
Old airplanes have plenty of worn-out stuff, and this problem was addressed by Cessna and maybe others a long time ago, via service bulletins.
 
Always treat a prop like a loaded gun. All it takes is a loose P-lead on a mag, or some other mag grounding issue, and you've got a live engine.
 
Cruzinchris said:
Turns out the key could be removed while in any position in addition to OFF. Apparently it was still R.

Some time ago I noticed that the key on my Beechcraft Sport could be removed in any position. My plane came with several keys. The one I was using was worn pretty bad. Using another key "fixed" the problem. .

Everyone should check this on their plane.
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Yep, I've had it happen too. The scary part was you could remove the key in the OFF position and one of the mags would unground. You could do all the hot mag checks you wanted, the engine would die if you turned it off, but as soon as you pull the key out it'd go hot again.
 
midwestpa24 said:
Always treat a prop like a loaded gun. All it takes is a loose P-lead on a mag, or some other mag grounding issue, and you've got a live engine.
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Exactly! I tell everyone I fly with to stay out of the propeller arc at all times and if they ever move the prop or around when someone else moves the prop treat it like the engine could turn over...
 
iamtheari said:
A broken P-lead has the same effect. Don't trust the switch, either. Assume every gun is loaded, every PTO shaft is turning, and every magneto is live.
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So what exactly does one do in this case?
 
apilotb said:
So what exactly does one do in this case?
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Don't touch the propeller unless you are ready for the engine to come to life. That includes having the throttle and mixture pulled all the way out to keep it from running away on you, standing where you will not be decapitated if the prop spins a few dozen revolutions, and ensuring there are no children or unleashed dogs in the vicinity who might get curious and come check out the spinning propeller.
 
I just approached the plane, verified the throttle and mixture are pulled out, verified the key is out of the ignition, etc. I start doing my exterior inspection, and get to the front of the plane. I need to rotate the propeller in order to view inside the cowling. I grab the propeller with one hand while standing back from the propeller as much as possible so that if it fires I lose perhaps my hand and nothing else? What else can you do to minimize risk of injury?
 
RingLaserGyroSandwich said:
I just approached the plane, verified the throttle and mixture are pulled out, verified the key is out of the ignition, etc. I start doing my exterior inspection, and get to the front of the plane. I need to rotate the propeller in order to view inside the cowling. I grab the propeller with one hand while standing back from the propeller as much as possible so that if it fires I lose perhaps my hand and nothing else? What else can you do to minimize risk of injury?
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switchBoth.jpg
 
I recently fixed a broken P lead on the left mag. Thought it was the switch. Found out something was wrong when I tried to shut engine down with engine. One shutdown switch to off let engine stumble then turn to on and pull mixture. As stated treat the prop like a loaded gun.
 
Assume once you move the prop, it will move on its own. If you have someone nearby who is competent, have him show you how he hand props his plane (such demos run periodically through Oshkosh near the Vintage barn)... in those cases they know (or hope) the engine will fire. Learn the proper place to put your hands and to stand.
 
When you must move the prop, move it backwards.
Think about this,,which is better a broken vac pump or a broken head?
 
asicer said:
switchBoth.jpg
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As a renter this doesn't really help me, but if I ever have my own plane I'll seriously consider an ignition system that isn't prone to the problem being discussed.

Skip Miller said:
If the ignition switch is failing, replace it. Easy-Peary...
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If I understand other users correctly, this isn't always easy to diagnose.

flyingron said:
Assume once you move the prop, it will move on its own. If you have someone nearby who is competent, have him show you how he hand props his plane (such demos run periodically through Oshkosh near the Vintage barn)... in those cases they know (or hope) the engine will fire. Learn the proper place to put your hands and to stand.
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This seems like a real suggestion... just fake hand-prop it at the beginning of your interaction with the front end after shutdown? That seems pretty easy once someone shows you... I like it!
 
I do a quick mag-check just prior to idle/mixture-to-shutdown. Flick the key to off just long enough to hear the engine stumble, then back to on quickly to avoid a backfire. Then, having confirmed that the ground still works, shutdown as usual. AND.. even then.. always assume the engine could start at any time when near the prop, anyway.
 
idahoflier said:
Exactly! I tell everyone I fly with to stay out of the propeller arc at all times and if they ever move the prop or around when someone else moves the prop treat it like the engine could turn over...
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Seems like a good idea. But how do you reach in to check the alternator belt, or lean underneath to place the tow bar, in something like a 172 without being in the prop arc?
 
idahoflier said:
Exactly! I tell everyone I fly with to stay out of the propeller arc at all times and if they ever move the prop or around when someone else moves the prop treat it like the engine could turn over...
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I used this for the safety section of our Young Eagles ground school: What's wrong with this picture?

upload_2019-7-16_19-39-30.png
 
As a 10 hour student........ why would he move the prop? Or was it inadvertent? I've never seen 'rotate the engine' on a pre-flight checklist.
 
There's not much to be gained in an opposed engine by moving the prop. And there's damage to be done in a radial if you move the prop and you don't have a clue what you're doing.
Lycoming recommends that any turning of the prop as far as preflight prep be done with the starter. Occasionally, you do have to move it to clear a tow bar or whatever, and then you need to be careful.
 
Jim K said:
As a 10 hour student........ why would he move the prop? Or was it inadvertent? I've never seen 'rotate the engine' on a pre-flight checklist.
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The nose wheel was probably chocked. He might have moved it inadvertently or just move it to the side to access the chocks.
 
Tom-D said:
When you must move the prop, move it backwards.
Think about this,,which is better a broken vac pump or a broken head?
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On a two-bladed prop, the maximum you would have to turn is a quarter of a turn. There is differing opinion on whether rotating backwards can damage a vacuum pump, but a quarter turn is unlikely to cause any damage. Besides, vacuum pumps will soon be a thing of the past anyway, so turning backwards is probably the best choice.
 
Jim K said:
As a 10 hour student........ why would he move the prop? Or was it inadvertent? I've never seen 'rotate the engine' on a pre-flight checklist.
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Yer probably not old enough to have ever pre-flighted an old radial
 
It's ~$5,000 to get a suit of knight's armor made. Might get some funny looks on the ramp though
 
and no one mentioned this...not even Tom. Most Bendix key switches have an AD...and must be checked that they ground the mags.

76-07-12 BENDIX IGNITION SWITCHES: Amendment 39-2575 as amended by Amendment 39-3024. Applies to all aircraft employing magnetos and using Bendix ignition switches listed in the table below except switches identified by four digit date code (new) adjacent to the model number or a white dot (modified) on the support plate adjacent to the Bendix logo.
Bendix Switches Rotary Action, Key or Lever Actuated
Switch Function Bendix (series) Part Numbers
Twist-to-Start 10-357XXX, 10-126XXX
Twist-to-Start/Push-to-Prime 10-357XXX, 10-126XXX
Push-to-Start 10-357XXX, 10-126XXX, 10-157XXX

Compliance required as indicated:

1. For switches subject to this AD, conduct the following checks within the next 100 hours' time in service and each 100 hours thereafter to detect possible switch malfunction:

(a) Observing regular ground run-up procedures, allow the engine to reach operating temperatures and perform a normal magneto check.

(b) With the engine at normal idle, rotate the switch key or lever through the "OFF" detent to the extreme limit of its travel in the "OFF" direction.

(c) If the engine stops firing, this indicates an airworthy switch.

(d) If the engine continues to run with the switch in the extreme "OFF" direction indicating a malfunctioning switch, prior to the next flight accomplish Part III outlined in Bendix Service Bulletin No. 583, dated April 1976, for Repair and Replacement or use an alternate method approved by Chief, Engineering and Manufacturing Branch, Eastern Region.

2. The aircraft may be flown in accordance with FAR 21.197 to a place where these modifications can be accomplished.

3. The checks required by this AD may be performed by the pilot.

4. Upon submission by an operator with substantiating data, an FAA Maintenance Inspector subject to prior approval of the Chief, Engineering and Manufacturing Branch, FAA Eastern Region may adjust the compliance times specified in this AD if the request contains substantiating data to justify the increase for the operator:

(NOTE: If the engine continues to run when complying with paragraph 1 and repair or replacement cannot or will not be accomplished immediately, the magneto (primary circuit) should be grounded in accordance with Bendix Service Bulletin No. 583, dated April 1976.)
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Turning it backwards is no panacea. You compress the cylinder in can still kick forward just at the point where the mag would fire. Some dry pumps have a direction specified, but that's talking about at operating speeds. You're not going to hurt them at the speed you're turning them. As I pointed out earlier and Tom alludes, you may need to move a radial to check for hydraulic lock, you better know what that feels like because if you just willy nilly pull the prop through, you'll break the cylinder as bad as if you started the engine like that.
 
Thanks.... negative on radial experience, but I am aware of the need to pull them through when they've been sitting. I couldn't figure a scenario where you would do it with a flat engine, but the towbar makes sense. Our club plane is handled by the fbo, so I haven't had to deal with that yet (they even wash the windows lol). Thankfully it has mag switches, but I suppose a mag check would be a good thing to add to the shutdown checklist.
 
If you move the prop backwards and hold it for a few seconds, the compression bleeds off and it won't kick forward. Besides, to get the impulse mag to fire, you'd have to turn backward far enough to engage the impulse stop (which might not be very far at all) and then it has to move forward 20 degrees or more to get it to fire.

And if the vacuum pump breaks because you turned it backward, that pump was far beyond wear limits and it was close to failing in flight. Don't buy pumps that don't have the vane wear inspection port; that port allows inspection at the first 500 hours and every 100 after that so that you can replace the pump when it reaches the end of its reliable life. I used those pumps in the flight school fleet and NEVER had a pump failure, and we turned props backward all the time.
 
Checkout_my_Six said:
and no one mentioned this...not even Tom. Most Bendix key switches have an AD...and must be checked that they ground the mags.
Click to expand...

I have found endless checks of that switch recorded in the logbooks of many airplanes, and since I am a suspicious guy, I usually check the switch itself to see if it really is a Bendix and if it really applies to that particular switch.

Most Bendix switches made after 1976 were made properly and the AD doesn't apply. Check the date code on the label in accordance with the AD.
Many were modified at the factory and have a white dot next to the label and the AD doesn't apply.
Many, many switches are not Bendix at all; they're ACS switches that are getting the wrong AD checks. ACS have their own troubles and the AD is here:
http://www.airweb.faa.gov/Regulator...B8ABD56539B4684886256A3E00759DBF?OpenDocument
 
Dan Thomas said:
I have found endless checks of that switch recorded in the logbooks of many airplanes, and since I am a suspicious guy, I usually check the switch itself to see if it really is a Bendix and if it really applies to that particular switch.

Most Bendix switches made after 1976 were made properly and the AD doesn't apply. Check the date code on the label in accordance with the AD.
Many were modified at the factory and have a white dot next to the label and the AD doesn't apply.
Many, many switches are not Bendix at all; they're ACS switches that are getting the wrong AD checks. ACS have their own troubles and the AD is here:
http://www.airweb.faa.gov/Regulator...B8ABD56539B4684886256A3E00759DBF?OpenDocument
Click to expand...

I learned about that white dot after one of our knuckle dragging club members twisted the key off in a Bendix switch.... The replacement switch was made in 1978.
 
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