I was always taught to drop the mags to OFF for a split second on mag check to test just that.  It was an airplane thing because of the danger from the prop (accidently "handpropping" from a bad P-lead).  There have been people killed from moving the prop even when the switch was OFF because of P-leads not being connected--especially the old ones with impulse springs.  I occasionally checked it on the helicopters, but not every time.  The checklist didn't call for it, so it was more the A&P in me doing that check.

From the video/pic, it sure does look like that key is on the OFF position at 2 o'clock.  Someone said that aircraft was new to them.  Wonder if they had a Raven I prior to that and he was used to seeing or turning that key in the 2 o'clock as that's "BOTH" on a Astro or Raven I......bad muscle memory or sight picture?  Kind of like how the little cap on the mixture on the R22 came to be--people pulling the mixture rather than the cyclic trim knob.

All my time was in Astros and Ravens, moved to the 206 about the time the Raven II came out.  Is the starter independent of the mag switch (i.e. can you crank with the mags in the OFF position?)  Of course if the mag switch is bad, anything is possible.  EDIT:  Wasn't there two starter buttons?  One on the collective and one on the side of the cyclic?  Any difference in wiring between the two?

I totally agree, that was a difficult auto, as auto's go. Of course everything is relative and this is aviation, so there will be intensive study of everyone's successes and failures.

Certain other aviation social media resources have reported that the front seat passenger's weapon somehow contacted the ignition switch, moving the key from BOTH to OFF, and at the same time the left mag had an intermittent P-lead, which chose to be bad for the initial portion of the flight, then chose to be good at right around 1:23 in the fateful video, thereby shutting off the only running mag.

What's a bit troubling is how does any part of the weapon (not even saying the muzzle) get all the way over there, particularly while the helicopter was running, since this would have been after the mag checks?

I would have to admit that I probably would not have noticed if this had happened to my ignition switch.

While I had previously postulated a dual mag failure, a closer look shows that a single mag failure (bad P-lead) is probably more likely. Looking at the back seater video plausibly shows that the pilot was concerned about the power the engine was producing, picking it up and putting it down a couple of times, and there might even have been some chatter about the engine on the soundtrack but it is tough to tell. This is commensurate with running on a single mag. I'd like to think I would have the presence of mind to do some more mag checks at that point. Manifold pressure (from the front seater video) did seem quite unreasonably high, 20" on the skids, and immediately going to 25" in ground effect. I've never had a bad mag on the ground, but I'd like to think those MP readings would have stopped me.

I have had a bad mag in the air, in an R22. The aircraft began to vibrate quite badly, but there was no vibration in the controls and, having just departed the airport, I judged it to be an engine vibration and not one associated with the rotor systems. I elected to return with what power I had and simply be ready to enter an auto if necessary. I did make it back OK. Unlike fixed wing aircraft, one thing we never do in a helicopter is switch mag's in flight. That's because when you find the bad mag your engine stops instantly and must be restarted with the starter, there is no windmilling from the prop, the transmission is connected to the engine via an overrunning clutch. The chances of starting the engine while in an auto that started at 1000ft are slim, especially for a student pilot I was at that time. So the switch is only there for pre-takeoff checks.

This guy has a really good video on how mag's work. He's a reeeeeaaaally slooooow presenter, though, so you might want to crank up the playback speed. He's also just released a new video on how mag's fail, but it is currently only available via the EAA webinar site. It should be up on his Youtube channel in the next couple of weeks.

I was taught not to do that, too rough on the engine. If you are patient you should see an RPM drop even with a brandy new mag.

In the Raven II it is and you can.

Yes, in the Raven II there are two of them. There is no difference, they are wired in parallel.

Yeah sometimes it would backfire if you did that......other option was to just shut it off with the key at the end vs. the mixture.  Then pull the mixture and run the starter to get the gas out.  Either way, not something I really ever did with students or pax, just occasional check as I never wanted that big 3/4" drive breaker bar to come around a hit my head or the tailboom when doing maintenance.

I've had a few mags go bad on the ground.....bad coil, broke a gear, and a snapped spring on the points.  Wear is more of an issue, but I always rebuilt them around 500 hrs whether or not they needed it.

Does your "Other Aviation Social Media" have access to SPAS or NPTRS?

Dude, this was a Part 91 operation, get serious, what the hell does that have to do with anything?

It is a normal procedure in big-displacement turbosupercharged radial and V-12 airplane engines I fly.

This is a world that closely controls how MP and RPM are used during the flight because of how easy they are to destroy themselves if they’re run incorrectly.

They also worry about things like “reciprocating loads” where the MP is low enough that the inertia of the prop is actually driving the engine, causing premature wear on the master rod bearing journals.

If the temporary removal of the spark at low MP and low RPM when doing a mag ground check were harmful to the engine, then it wouldn’t be done with regularity across the pantheon of engine models and operators.

R-1830 checklist:
Attached File


R-1340 checklist:
Attached File

Huh? What are you talking about dude? I am entirely serious.

SPAS and NPTRS cover everything. I can look you up in SPAS and you might only have a private. I can also look you up if you're flying for a 121. I can look up your aircraft by tail number or serial. I can even look at your airworthiness certs and 337's/STC's in addition to any occurrence, incident or accident you or the aircraft have ever been involved in.

You're saying that people are saying things that we aren't privy to on social media and I am asking if the people saying these things are inspectors or not, i.e. people who probably did the investigation. Inspectors have access to SPAS and NPTRS. There are GA inspectors too. I am one.

If they are actually inspectors and are posting information, cool. Point the rest of us there too.

You say your are a GA inspector and have access to these otherwise non-public data repositories. If so, then why don't you look up this incident and tell us what happened?

I said no such thing.

I have no idea. Some person on the internet posts something. True? Rumor? Bullshit? Who knows. My provenance is "social media", which of course is no provenance at all.

It would seem that somehow I pushed one of your buttons with my post about the bumped switch, which generated some snarkiness on your part (that's how I felt, anyway), which I then amplified.

So how about we both turn down the gain a little and maybe address what your original concerns are? Did someone say something they shouldn't have on the internet and I picked up on it? Or do you take exception to hypothesizing about aviation events like this? What's the issue? How can I help?

eta: PM me if you like.

No PM necessary. We are adults.

I was simply asking because sometimes the real story comes out and it is different than the investigated one, or maybe the IIC or an assistant was talking about it and I was interested. My buttons were not pressed, I was simply asking where you were hearing that from and apologize if there was misunderstanding or implied snarkiness. I know there are a couple other inspectors on the website and perhaps the one I know is here and works that region was talking about it.

Having me go onto SPAS and looking at the investigation without an official need is wrong and against the law. It is one of those deals. I'm not going to throw away my GS13 for posting what I might find online either.

SPAS
NPTRS
SAS
OWL
CHAT
MSAT-A

Let's rock babeeee!

You forgot CASTLE and eLMS.

And right now for us airworthiness guys... IACRA don't know if you ops guys are renewing IA's where you work.

Actually IACRA is pretty easy and I wish all the IA's did their stuff in IACRA because it perfectly flows into SAS. First IA I renewed I was like, "Wait... that's it?" Not like AWC where if you're doing a N number change or a ferry permit and you click before the spinny thing stops you're fucked.

There is a plan in place to make IACRA suck. I guarantee it.

I am at work and can not watch the video. I assume this is the one from Texas. The guy in the video posted in GD  There was a meber here on the helicopter who was a shooter who swapped with his friends who made the crash video. This was right after it happened.

Those are my friends on the flight.
The guy in the back seat was wearing my gopro.

Here is the video from my hunt which we had just got done with before they crashed:
https://www.youtube.com/watch?v=UxsTp1pmh30&t=3s

Awesome video, man that looks like fun!  



Not to step into the shit storm, but I watched the video that crzapy posted, and took a still of the key position.  It looks to be on "Both", or the 5 o'clock position in this shot, correct?
Attached File


@crzapy do you remember if they shut down between hunts, or did they load up hot?

If they didn't shut down, I'm wondering if the key could have been bumped during the loading/unloading.  That might explain why it didn't get caught by the pilot?  Pure speculation on my part.

The fuel state was higher in the crash video. That means they probably shut down to refuel, although hot fueling is not unheard of.

It's extraordinarily unlikely that a bump to the key could cause it to turn three whole positions. It's just as unlikely that any part of the passenger or his equipment would have intruded into that space. If you've ever sat in an R44 you would almost certainly agree.

wow...I am impressed the flying eggshell made it

They are actually very impressive and capable little helicopters. If you've never flown one you should.

They’re great helicopters, but as you pointed out, they are often flown by inexperienced pilots and operators which inflates their accident rate.

My gripe with them is the fan scroll, fly wheel and hydraulic fluid that smells like vomit.

Good point about the fuel state.  Probably not hot refueling a civilian helicopter with 100LL.

I’ve flown in R44’s, and while I do agree it’s unlikely, strange things happen in an environment with gun stocks, slings and gear.  It was just a thought, it’s hard for me to imagine getting that far with the mags off...

Too true.

Not following...what's the problem with the fan and the flywheel? And are you sure it's not your passenger you smell? Because, having refilled the hydraulic reservoir myself, I actually don't think MIL-PRF-5606 smells bad. Also, it should not be leaking so badly you can smell it at all.

Maybe he means the transmission fluid?  That blue-green stuff is nasty!  Apparently it's the same stuff used in some Porsche transmissions.

Oh yes, that I believe! All gear oil smells like vomit no matter what kind it is!

The stuff in the Robinson gearboxes is MIL-PRF-2105E. Swepco 201 is the brand that Robinson resells under their part number. Couldn't tell you if Porsche uses it or not.

But it should not be leaking and your helicopter should not smell like vomit unless someone puked inside

If the rotor boots don’t have a solid seal when you service them you’ll smell vomit. Something about being exposed to the air causes the fluid to turn.

Taking off the fan scroll requires the removal of over 100 1/4” fasteners, it’s a huge pain.

Installing the flywheel requires you to put it in the oven, heat it up till it expands and quickly get it seated on the crankshaft before it cools.

One time I complained to a Robinson engineer about how hard they were to work on and he had an infuriating response:  “Why do you care? It’s just more billable hours for you.”

It's Dexron III ATF in there. Never had that smell like vomit. And if the spindle boots don't have a solid seal they are either empty (very bad) or you've been topping them up so the ATF is not all old.

I recommend the winter boots for anyone flying below freezing.

Is your shop an authorized Robinson service center?

Many moons ago, the shop where I earned my A&P was the first Robbie service center in East Texas. I worked there from 05-09 but they’re not in business anymore.

Can someone to explain me how the engine can run with the mags in the -off- position, i.e. both P Leads grounded?

Yep, that's the stuff.  It's been a lot of years, couldn't remember the brand.  I may have worked for an operator that bought that stuff from a vintage Porsche repair place vs. Robinson.  It would get everywhere when students hung on the rotor brake and burned out the rear seal.  Then it would run down the firewall, get behind the seats, all over that belly inspection panel, etc.  YUCK!!



I had a long handled, but tight tolerance Snap-on box end wrench and a 12" extended driver with a No2 Apex bit.  I could get most of them with that pretty quick.  But the worst part was (at least back them), RHC painted those scrolls AFTER they put the hardware on.  So imron was gooped all over them......so you had to use a pick tool to clean out the Phillips heads, and work to get a wrench on the nut.  Then the first time you removed it, paint chips were everywhere and it looked like sh!t from then on.  

Obviously there had to be at least one broken P lead.

If you have read the entire thread, you would know that the story put forth by the pilot, via friends of the pilot (not me!), via social media like this forum (so grain of salt and all that), is that it was a broken left P-lead.

That the engine was only running on a single mag is pretty well substantiated by the video evidence. Look at my post up near the beginning of page 2.

One thing I should have put in that post is that a broken left P-lead is by far the more dangerous of the two, because pretty much every Lycoming (and Continental, I believe) starts off of the left mag, and with a broken left P-lead a modern Raven II will happily start with the key in OFF since the starter buttons are located on the cyclic and collective.

This makes one wonder whether he not only blew off his mag checks, but also had the key in OFF when he started it.

Attached File

The way I understood it is both P-leads were connected, but there was a bad ground somewhere in the system, thus making one or both ineffective at times.

The mag switch is is supposed to be "fail safe" by always being "hot" unless you turn it OFF (and ground it.).  It doesn't need to be turned "on" (or R, L, or Both) for the engine to run.  That way if there's an internal problem with the switch, a wire, etc, the mags are NOT grounded and thus "hot".  Think of that switch being wired backwards......turning them OFF completes the circuit (or R grounds the L mag.)  So if one or both P-leads have an intermittent ground or are not connected, the switch in the OFF position doesn't ground both mags.  You can stop the engine through fuel exhaustion, not by cutting the ignition.

In this case, it sounds like one or both of the mags had a intermittent ground to the p-lead(s).....whether it was the switch, the mag connection, or the wire(s).  At some point, that key got switched to OFF.  Whether between flights, inflight, whenever, the engine kept running, and even could have been restarted since that model has a starter button on the flight controls vs. turning the key.  So, it was flying on one or both mags with the intermittent failure to ground, then it eventually grounded like it was supposed to do and killed the ignition.  

I was never a fan of having a bunch of crap on the key ring for that reason.  Covered the letters on the side, switches, would get in the way of the vent knob.  So people would fling the keys or fob out of the way.....seemed like trouble waiting to happen.

OK, that makes sense. So we had a failure not caught due to a lack of runner procedure.
I was questioning the ones that were saying he forgot to turn the magnetos on and flew away.

As I recall, I used ignition wrenches and a 1/4” drive socket with a wobble bit to get some of them off. That gray paint was so damn thick!

Interesting commentary, thanks guys.

About the preflight checks- how often are these performed?  Every engine start, every take-off, daily?

That's perfectly possible too......if a p-lead is bad in that helicopter, and the switch is OFF, you can still start the engine because "START" is NOT a keyed position.  There are two starter buttons not associated with the ignition switch.

Just in case you don't understand, these break down into more than one procedure. The following answer is helicopter specific (it will differ a bit for fixed wing).

Pre-flight check (walk around, check everything): a full one at the start of every day. Some would say a full one before every startup, but honestly if the aircraft is working continuously all day (e.g. rides, sling work, utility inspection, etc.) subsequent checks are more limited and concentrate on fluid levels, leaks, Telatemp strips, as opposed to touchy feely on every rivet. Student pilots always do a full one, though. I have a set of mechanics gloves in my flight bag for doing these on hot engines.

Pre-start checklist (after the pre-flight, before starting the engine): the whole thing, every time. On an R44 this check takes only about 30 seconds for the entire sequence, a minute if you are slow

After-start checklist: every time, it's only a few items like clutch switch, alternator switch, oil pressure, etc. It takes 10 seconds.

Pre-takeoff checklist (after engine start, before you leave the ground): this is really what you are asking about, and really the root of this accident. And the answer is: every time before the first takeoff after an engine start. MP chart, mag's, sprag's, hydraulics, low rotor RPM horn. It takes maybe 1 minute to do. You only do this once per flight, not every time you land and takeoff again if your operation involves multiple landings, as long as you are not shutting down in between.

This is a great post, and lays it out really well for fixed-wing pilots.  Thanks.

One thing that I keep wondering about is going from .mil turbine helicopters to .civ piston, it would be pretty easy to forget one of the additional items you have on a piston engine vs a turbine.

For me, I wouldn't be safe if I got out of my jets and back into a light twin, at least without some good instruction, revisiting the basics and very careful adherence to the checklist.

Yes, with a defective P Lead it would start.

Maybe the cell phone too. They use to have a "ground use only" sticker on them if not stc'd which I can't imagine this one has.

I think those two items will be the least of their problems...

When my brother went down he was almost violated for having expired sectional charts on board. The FAA loves to have a fit over minutiae.

Oh, believe me I'm very well aware.  I deal directly with the FAA (among other, even more pedantic agencies) in a management role at my current employer, and have for several years.

I said that that would be the least of their problems.