Deadly Switches
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- Опубліковано 25 жов 2024
- That ubiquitous key-operated ignition switch in most single-engine piston airplanes is fraught with peril. There are two different designs that have different failure modes and are subject to different airworthiness directives. Yet one critical failure mode is unaddressed by any of these ADs and has resulted in death, serious injury, and costly property damage. Maintenance expert Mike Busch discusses how and why these switches fail and what you can do to protect yourself from the deadly consequences. If you own or fly anaircraft with a key-operated ignition switch, this webinar is a must-see. Savvy Aviation offers Professional Maintenance Services to owners of GeneralAviation aircraft, such as: SavvyMx (Professional Maintenance Management), SavvyQA (Expert Consulting), SavvyAnalysis (Engine Data Analysis), Prebuy services, and Breakdown Assistance. Savvy also publishes a monthly newsletter with lots of interesting information for the general aviation enthusiast; subscribe to it at www.savvyaviat... or text the word "Savvy" to 33777. This webinar was hosted by the Experimental Aircraft Association (EAA).
Pro tip: watch this at 1.25 speed. Thank me later.
2x ftw
Most A&Ps move at the speed of smell
Lol how
The 2x worked great! Lol
2x for me!
Completed my annual in December 2023. IA found my key could be removed in any switch position. Replaced it and I am VERY happy and THANKFUL for his thoroughness.
My ACS switch was only 2 years old on my RV build and had about 200 flight hours on it. On a high altitude flight out of Colorado over a broken overcast the switch randomly engaged the starter about an hour into the flight totally frying the starter and shorting out my entire electrical system. Got to an airport using the chart on my phone and the aircraft compass!!! I ripped that sucker out and went with a push button starter switch and toggles for the mags.
Not graphite as a lubricant for the ignition switch mechanism. I have dealt with this for years on ignition switches on cars, because they get worn as well and will sometimes come out without being in the latch condition. I would actually put slick Lube or even Dielectric grease, that will provide lots of internal lubrication. You can even Jam slick Lube in there and Slick Lube hasn't at least some Teflon. And Teflon would be a wonderful addition to any ignition switch mechanism. Just so you know in case you're not aware, slick Lube is basically Teflon infused Dielectric grease. You can use it for door latches as well and went because when it heats up in the summertime it'll actually liquefy a little bit and spread to other parts of the lock mechanism.
Amen. It has been found the graphite only works insofar as it's contaminated with oil. Truly dry graphite doesn't "lube."
I always started the preflight in the cockpit and checked the ignition switch(es) first. And yes, I once found one on R with the key removed.
Thx for the comment, we all should on top of this issue.
I started flying fifty years ago and can't say I've heard of this problem. Thanks for the info, I'll be mindful in the future. That point about overloading key rings applies to all vehicles and equipment.
Electroair ignition switch eliminates the ad and no key required. The nice thing about it is you can prelube and rotate prop using starter with both mags off and pressing start button. It’s a pretty simple solution.
It never ceases to amaze how even minor parts of aircraft can cause such serious problems. Also, while the combination of lock for security and "turn the key to start/control the mags" makes sense for customer convenience and fewer. parts, it seems like yet another relic of the "bad old days" that should be replaced with two separate components each of which do their one job better than the combined device.
Yes I agree. I think most twins are like that where mags are turned on and off with a toggle switch. I know I would prefer switches for the mags and a separate button for the starter.
Nevertheless, even a design of 2 separate magneto switches and another separate starter switch will not prevent your aircraft from having a hot magneto in case just one of your switches fails or if you got a broken wire. I assume you would just replace one single part that can fail by three, without adding any redundancy.
Want to see just how many general aviation stupid design flaws and pilot errors there is in general aviation, go to “plane crash map” and type in your favorite state. Dan Gryder can never fix all that human stupidity that’s never going to change.
One of the nice features of this relic design is that it's easier to locate (especially for student pilots who are more familiar with cars) which switch controls the magnetos.
Excellent. The AD has never showed up in my AD search but would be applicable to my aircraft. The AD doesn’t address key retention though.
When I was a little boy my Dad instilled in me to ALWAYS STAY OUT OF THE PROPELLER ARC AND TRHEE FEET AWAY, ALWAYS. Years later a friend was learning about hand propping and with the switch off, the engine fired for about 1-2. Seconds. Scared the crap out of everyone but no injuries and an engrained lesson learned. You can’t trust the prop because the engine is always hot!
When I first started working on GA aircraft I was always taught to treat it like it's hot even if it's in the off position. It's a great habit to always take extra caution when operating or inspecting.
Another great seminar. Thanks Mike!
There is an Electroair STC to replace the key switch with a toggle switch and push button. The switch panel can be installed with or without the electronic ignition system.
Yes - the use of a key switch instead of switches for mags is asinine
The reason why the left and right on the mag switch is backwards comes from the days that airplanes were hand propped. The convention for the engine manufacturers is to install impulse coupling on the left mag. You would hand prop the engine on the left position and then be able to immediately click the switch to both when the engine starts.
This brings up the question, if the accident airplane's mag switch was found with the key removed and the right mag hot, the engine would likely fire is with a big kickback. There might be enough energy to generate a spark while turning it over by hand, but the non impulse coupled mag would fire well before TDC and cause a kickback. Does the accident plane have impulse couplings on both mags? I think some Bonanzas with Continentals have impulse couplings on both. Did the pilot get killed from a kickback? Or did the engine really start?
@1:04:43 - They probably picked up the habit from watching too many WWII movies turning the bomber props before lighting them off. Lol
20:32 Wow it's interesting you can just walk into a mechanic's shop and find keys to actual planes hanging up on the wall. Keep in mind a key is just a physical password, and a picture is enough to copy it 😅
Why do the cutoff check at run-up? What if the check fails? Are you returning or just go on with the flight and hope to remember to report it afterwards? What if the engine quits and will not start again immediately? Or the ignition is not put back to both and you do the take-off on one magneto. I learned to do this check after a flight when you want to stop the engine anyway (same check, back to both, then idle-cutoff).
I was trained to do this Mag Switch check as part of normal shutdown procedures prior to mixture cutoff
Same, I thought it was standard for all shutdowns to do what we call a 'live mag check', but have seen several examples of this not happening recently. Although, this would not have helped the gentleman at the start of the video, as he was able to remove the key in the wrong position
The ignition key and the baggage door key on Cessna 172, 182 may be differant - if the ignition key has double side and the baggage has only one side. The baggage key may fit in the igintion and turn the starter, but will not remain there. So if you use your baggage key instead of the proper ignition key then it will come out of the ignition.
An old pilot friend had a 1965 Chrysler Valiant. "the original key was SO thin, it only had one side."
What about the issue of making duplicate keys from an old one - 'cloning error' if the original is worn, most hardware stores are just duplicating this worn state. I think there may be some kind of lock code that a lock smith can use to cut a new key from scratch - a new baby - not a clone.
The big problem is, how would Joe Average KNOW if a Bendix brand switch installed - without removing it to see eg the brand on it.
Some years ago 2006 I bought a homebuilt aircraft ( Europa Mono wheel ) in Florida, the builder and pilot had a engine stoppage in Dec. 2001 in the first year after it's construction. The engine stoppage was put down to a faulty ACS Mag switch, I don't know what the failure mod was for this but is this something others have experienced? The airplane had only minor damage in the off field landing btw.
ACS is Aircraft Spruce. When you buy a new switch from ACS, it comes with a new set of key. Replace the switch and keep your mind at ease.
Could these engine-start mishaps be prevented by shutting down the engines by leaning, and leaving the mixture controls at full lean while manipulating the props? Assuming 100% compliance with this shutdown procedure, does this solution reliably prevent engine start? If so, did the NTSB investigate if this shutdown procedure was followed?
If this isn't reliable, what about closing the fuel valve before or after shutdown?
THANK YOU THANK YOU THANK YOU!!!! I HATE those damned combination mag switches!
I always replace them with two toggles switches, one for each mag. I do this so that each mag can be controlled independently for inflight leaning checks AND because you can simply bat them both off with a single swipe.
Those switches are heavy and you find them even in airplanes with no electrical systems.
I have a pile of them. They SUCK.
Food for thought, so when doing a mag check and you switch the ignition from both to the L position have you switched the left mag off and running on the right or have you switched the right mag off and running on the left and vice versa when switching to the R position ?.
Mike, in order to be sure that all fuel is purged when the mixture is moved to idle cutoff, does it make sense to advance the throttle to an above idle rpm setting prior to idle cutoff to provide more propellor rotations (and more air pumping) to clear the cylinders?
Especially important for us hand-propers!
But what about Rotax? Where you have to rotate the prop in order to check the oil.
I was told to move the prop with flat hand and not in the propellor plane of rotation.
Thoughts?
Rotax uses electronic ignition, not magnetos, though -- right?
Im confused
does this key barrel over ridé the Grandé Mastér Switch ¿¿¿¿¿
The 3 blade on my IO-540 always comes to a stop with a blade in the down position preventing the tow bar from being installed without moving the prop. I move it with caution.
Remount your prop at 180 degrees offset.
@@lancairESflyer And what do you do about the master dowel and engine balance?
@@postulator890 Hopefully he was joking.
Any a&p who is his weight in dirt knows that the functional check includes not being able to remove the key in any position except the off and to jiggle the key to make sure the engine won't fire. But he is correct it does not say that in the ad or the service information. I can't tell you how many ignition switches I've replaced because the key could be removed in any position and owner said it's been like that for 10 years well not going to be like that anymore cuz I'm doing the annual.
I think the reason why R is on the left and L is on the right, is because when you turn the switch to START, it's only does the Left mag - because of the impulse coupling. Like in the newer Archers without a key - you only turn on the left mag for starting.
There is a jumper on the back of the switch that can select just left mag when starting if you have impulse or slick-start or if not attached it uses both mags. You can use that if you have an electronic ignition.
It would seem a simpler and more robust switch system is in order. For example: a master ignition enable using a key switch, and one toggle switch for each mag. The position of each toggle switch would make its state visually clear. The key switch, having only one function, would have a nice wide angle between its on and off positions, making it mechanically easier to ensure its proper electrical function and ensuring the key could be removed only when in the off state.
What a heartbreaking and needless accident.
OK, when this occurs it could be a hundred hours before this is checked if there was a directive.
Also the pilot may not even be aware there is a problem. You don't pull the key until it's in the off position.
Maybe there could be an indicator light on each mag, maybe a duel light duel colour glob indicator for each mag.
Rotax is specific that the prop should not be rotated in reverse because reversing the oil pump could collapse the hydraulic valve lifters. That being said, reversing just to move the prop out of the way is probably irrelevant, and it's an electronic ignition engine. Just to say that some instructions can be excessively regarded.
Thank you!!!
Many failure modes. ✔️
The r and l are reversed based on their location on the engine and it is referenced from the front would be my guess
An Annual inspection is for that moment in time of inspection the aircraft is airworthy from the past inspection to this inspection. Not to the next inspection in the future... When the next inspection is due... Past to now not now into the future.
Maintenance by osmosis is a real thing, , , "I bought it that way honest!"
This switch could have been failing to ground the mag for a long time as a cold engine will be less likely to light off after it sits.
Pilots and systems engineers tend to nit pick. Is that a turboprop at 8:36 in the video? Why?
No one ‘really’ wants the NTSB to get involved, so there are likely incidents that don’t get reported.
Could a gravity fed engine allow the engine to fire if the fuel selector was left on with a hot mag and and prop pulled even though it had been shut down by pulling the mixture control?
No, not counting a hot, recently ran engine that may have vapor.
Why would anyone move a prop as part of a preflight? I know they do it for radials to prevent hydraulic lock but there’s no reason to do it on a flat engine. As someone who has hand propped champs and j3s it is drilled in to your head to treat every prop as hot.
My flight school taught me to turn the prop over a few times to help prime before a very cold start.
@@samomiotek7210 without chocks and checking throttle closed and treating it like it could start that’s a really bad idea.
Sometimes you have to move the prop to fit the tow bar or examine the cooling air intakes.
Agreed.
@@DrDeFord
Yes, everytime my three blade comes to a stop, one blade is in the way.
If you put the switch to off and the engine still runs, it could be a bad p lead or the switch
thanks Mike. you are our savoir. every pilot + machanic should be watching these. unfortunately do not. I have watched most of your videos and some cases more than 1x.
A lock will retain the key until it doesn't. A locksmith should have looked at the lock. A professional locksmith advised me to not keep the key to my old car with the main key ring when operating a car.
Its puzzling that he doesn't know why the L and R are opposite on the switch. That boggles my mind. Thats as basic as it gets.
Would this mean that the engine was not previously shut down by pulling the mixture control and starving the engine of fuel?
Even if you shut off the mixture, there can still be gas in the injector's lines seeping into the cylinder. On my IO360 I can start the engine without adding any fuel during a hot start, say up to 1 hour after shutting it down.
No, it means the pilots were not doing a mag GROUNDING CHECK before each engine shutdown. The switch could fail open OR the P-lead could be broken. Either leaves you with a hot prop.
Please could you make these into podcasts?
This AD was more of an ND . Assume all mags are hot , and all guns are loaded .
and the FAA claims "certified" parts are better and safer and justify extortion pricing..........
Yeah, I they really stretched this topic out.
Magnetos should be consigned to history. Certification of aircraft is supposed to make them safer, but it locks them in the past instead. The last place you find magnetos should be chainsaws and other similar small equipment with no electrical system. New aircraft should be required to have FADEC with port injection and electronic ignition. A new 172 is half a million dollars and comes with 'technology' you couldn't sell to a car buyer 30 years ago, because it's garbage.
This wasn't a failure of the switch. This was an instructor failure.