Blowing our mags with Nitrogen

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woxof

Pre-takeoff checklist
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woxof
I am reading an interview in the NTSB docket about a plane crash where there was difficulty with engine starting due to what was perceived to be moisture in the mag. Nitrogen was used to 'blow out'(or dry out) the mags and the engines subsequently started......

".....I've been told via interviews that they didn't like to start because they had moisture in the magneto or the mag, and they would have to blow them out with nitrogen to get the spark in there to get the engines to light off. And this seemed to happen on mornings that were with high humidity and things like that. Are you aware of that procedure to blow out the mags......."

"Yes. I'm aware of it. I wouldn't characterize it as a B-17 only problem or a common problem, but it is something that happens on all of our radial engines. If it's been raining, for instance, 1and we've been sitting for a couple of days, any of the airplanes can get a lot of moisture. The mag itself is fine, but they're not steel mags in the way that moisture can't get in. So they need to be dried out before we can fly the airplane."


Has anybody heard of this procedure and is it only on certain older mags where it would be applicable?
 
woxof said:
I am reading an interview in the NTSB docket about a plane crash where there was difficulty with engine starting due to what was perceived to be moisture in the mag. Nitrogen was used to 'blow out'(or dry out) the mags and the engines subsequently started......

".....I've been told via interviews that they didn't like to start because they had moisture in the magneto or the mag, and they would have to blow them out with nitrogen to get the spark in there to get the engines to light off. And this seemed to happen on mornings that were with high humidity and things like that. Are you aware of that procedure to blow out the mags......."

"Yes. I'm aware of it. I wouldn't characterize it as a B-17 only problem or a common problem, but it is something that happens on all of our radial engines. If it's been raining, for instance, 1and we've been sitting for a couple of days, any of the airplanes can get a lot of moisture. The mag itself is fine, but they're not steel mags in the way that moisture can't get in. So they need to be dried out before we can fly the airplane."


Has anybody heard of this procedure and is it only on certain older mags where it would be applicable?
Click to expand...
They must be pressurized mags to start with. Pressurized mags can go higher as in the B-17 /B-29.
But to blow out moisture, not really. the vent is a fitting that should prevent this.
 
I knew a guy with an old Stearman who would always put a small space heater in the cowl (rear of engine) the day before flying it. This plane never sat outside. He would always fly it around the July 4th holiday, be 90 degrees with 85% humidity in that hangar and out comes the space heater.
 
woxof said:
Has anybody heard of this procedure and is it only on certain older mags where it would be applicable?
Click to expand...
It's "quick" fix just as using a heat gun/hair dryer to dry out the mags. However, in the case of that particular B-17 they had a lot more "quick" fixes in the mix than just drying out a mag with nitrogen.
 
C-54’s had somewhat similar P & W engines with B-17’s.

C-54 had R-2000 s and B-17s had R-1830s.

Mags were on the front of the engine.

First time I’ve seen the issue I was astonished by the amount of water that would

pour out.

One of the “Old Guys” spraying water displacing CRC would take care of things.

It affected how we did Mag Checks.

ALWAYS after landing and in normal just before take off.

NEVER before loading passengers.

If it was done it seems condensation would form and render the mag useless

for the next run-up.

I always wondered if it was water already in the mag and the run up moved it

around.

With a cold engine and cold mag it would not boil off.

Guess all aircraft have their quirks.
 
with todays modern mags it is near impossible to get water in a mag.
They all have vent plugs at the bottom of them housing with small filter in it.
The TCM, TSIO-360 actually has a fitting at the top of the mag that attaches a hose to the induction system that is pressured, several other Turbo charged engine do also.

OBTW the mag looking things in front of the Radials are actually distributors not mags, the mags are on the engine accessory case.

I would be presently surprised if you could tell me the firing order for the 4360.
 
Tom

I agree with water comments and don’t ever recall water in light aircraft mags.

On the R 2000-4 and I think the R 1830-92 those things are the mags.

Other models did have them in the rear.

These were High Tension Systems.

I’m clueless on “ New ? Stuff” like the 4360 that was likely Low Tension.

Guessing the order can be determined something like the

“ add 9 or subtract 5” for 14 cylinders or “ add 11 or subtract 7” for 18 jugs.

With the 4360 I’d have to take my shoes off!!!!
 
woxof said:
I am reading an interview in the NTSB docket about a plane crash where there was difficulty with engine starting due to what was perceived to be moisture in the mag. Nitrogen was used to 'blow out'(or dry out) the mags and the engines subsequently started......

".....I've been told via interviews that they didn't like to start because they had moisture in the magneto or the mag, and they would have to blow them out with nitrogen to get the spark in there to get the engines to light off. And this seemed to happen on mornings that were with high humidity and things like that. Are you aware of that procedure to blow out the mags......."

"Yes. I'm aware of it. I wouldn't characterize it as a B-17 only problem or a common problem, but it is something that happens on all of our radial engines. If it's been raining, for instance, 1and we've been sitting for a couple of days, any of the airplanes can get a lot of moisture. The mag itself is fine, but they're not steel mags in the way that moisture can't get in. So they need to be dried out before we can fly the airplane."


Has anybody heard of this procedure and is it only on certain older mags where it would be applicable?
Click to expand...


Mags have been around for at least 100 years now, they were around for at least 20 years when this airplane was built. Those planes flew in all types of weather, they knew how to keep water out of those mags then. I was mortified when I read that paragraph in the original report. That statement, and the acceptance of something like that as SOP, is why pilots, or worse, passengers die. We need to smarten up.

A quick look at the crash mags make it clear why they were leaking.
 
I’m not convinced the water leaked IN.

Having seen and dealt with it my thought is condensation is the culprit.

However; one dead mag will only kill 14 out of 112 Spark Plugs.

That leaves you with 3 engines that should develop full power and one

that should make partial power.

Presuming the aircraft was not at Max Gross the aircraft should be able to

maintain flight.

The C-54 is somewhat similar and certain things were checked in preflight

planning.

Takeoff Performance with one engine inoperative must be 100 ft /min

or reducing weight was required.

Seems if you are airborne at less than Max Gross than just feathering the

Engine should suffice.

Possibly even shutting off the bad mag would allow flight.

Sounds to me like Crew Proficiency was not in the picture.
 
They lost #4 and feathered it, then #3 quit and it didn't feather. The aircraft was on a right downwind and lost #3 just before turning base, and my guess is keeping in the air required more thrust on #1 and #2 than they were able to counteract.

It took out the approach lights, came down short of the threshold, went off the right side of the runway, and into the glycol tanks and equipment.

The mags on both engines were improperly gapped, and the p-leads had previously pulled out of the terminal fittings at the mags and were held in place by a single strand of safety wire. This allowed the p-leads to intermittently ground to the case. There was detonation damage on #3, and other problems on both failed engines.

It broke my heart looking at the photos of those engines and reading the description of the deficiencies in maintenance and operations. That proud bird deserved better, and I was shocked that the Collings Foundation had risked the lives of their customers for so long and in such a careless and frankly criminal manner.

When I flew on their bombers, like Magman I figured that if they lost an engine it would be no big deal and we would land safely. I never considered that two on the same wing could fail and a prop wouldn't feather. Between the two pilots they had over 5,000 hours of time in the B-17. The captain was also the Director of Maintenance.

I've never read a NTSB report that left me more sad and disillusioned.
 
3393RP Thank you. I see the picture now.

My comment was based on my belief that water in one mag would not

cause the accident.

Unfortunately; your comments tell me that the whole operation

left a lot to be desired.

I guess they could have safely landed with no problem IF they could have

feathered #3.

A dead non-feathered engine creates a tremendous amount of drag.

In their configuration I can’t see how they could possibly stay above Vmc.

The C-54 included a check of the Feathering System on Run up.

Very unlikely all these issues likely didn’t present all at once.


I feel your pain and anger for another reason.

Your comments on the Collings Foundation really bummed me out.

They were held in high esteem by me primarily due to their video of

the flight of their F-100F with “Bud” Day.

He was a friend.
 
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