Damage from Ingested Cowl Plugs?

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techflight

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techflight
A renter today neglected to remove the cowl plugs from my Piper Archer, ingesting them into the engine bay. He then proceeded to somehow complete a one hour flight and landed back without issue, oblivious the entire time (even remarked how everything worked great).

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I'm at a loss. The only obvious damage beyond the now dead battery is the alternator belt which snapped completely off and will need to be replaced. The shop will of course be doing an inspection. I am worried about any possible long-term damage that might come up later (that might be impossible to pin on this incident)-- is there anything I should be concerned about (not sure if this is even a valid concern) or ask the mechanics to look at in particular?
 
I’d be concerned about renting to that person again. I doubt the engine was damaged. I’d check things like aircleaners and make sure cylinder fins are clear. I’d also get cowl plugs that are connected by a strap. Make sure the strap goes over one blade so the plugs are launched clear on start up if you get another renter who clearly doesn’t preflight.
 
PaulS said:
I’d be concerned about renting to that person again. I doubt the engine was damaged. I’d check things like aircleaners and make sure cylinder fins are clear. I’d also get cowl plugs that are connected by a strap. Make sure the strap goes over one blade so the plugs are launched clear on start up if you get another renter who clearly doesn’t preflight.
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Got it, thank you so much for the input!

These cowl plugs were connected by a strap, completely agree ideally the strap would go over a blade but I can't control how each person who uses the airplane positions the strap unfortunately.
 
A Conti 172 had been flying regularly with no issues. One day the owner abruptly

put it up for sale. Since I had been flying it and doing the Mx I recommended the

aircraft to a friend. The first oil change the screen was loaded with aluminum.

My friend and I were both shocked! He sold the aircraft as is.


Years later I heard the tale of the former owner landing a taxiing to a secluded

area and exiting the aircraft and looking for onlookers. Then he took the cowl

plugs out!


My guess is you have no way of knowing what the oil & head temps were during the

renters flight. At a MINIMUM; my suggestion is to do oil analysis, scope all

cylinders and check screen/ filter.
 
Magman said:
A Conti 172 had been flying regularly with no issues. One day the owner abruptly

put it up for sale. Since I had been flying it and doing the Mx I recommended the

aircraft to a friend. The first oil change the screen was loaded with aluminum.

My friend and I were both shocked! He sold the aircraft as is.


Years later I heard the tale of the former owner landing a taxiing to a secluded

area and exiting the aircraft and looking for onlookers. Then he took the cowl

plugs out!


My guess is you have no way of knowing what the oil & head temps were during the

renters flight. At a MINIMUM; my suggestion is to do oil analysis, scope all

cylinders and check screen/ filter.
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Yikes, thanks for sharing. It's almost due for an oil change, so I'll get that done now with an oil analysis while it's grounded anyway.
 
Magman said:
My guess is you have no way of knowing what the oil & head temps were during the
renters flight. At a MINIMUM; my suggestion is to do oil analysis, scope all cylinders and check screen/ filter.
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My thought also concerning CHTs with the cowl plugs in place. There may be damage that won't be readily found. Keep an eye on the hot idle oil pressure. Low oil pressure when hot is an indicator of bearing wear ...
 
Daleandee said:
My thought also concerning CHTs with the cowl plugs in place. There may be damage that won't be readily found. Keep an eye on the hot idle oil pressure. Low oil pressure when hot is an indicator of bearing wear ...
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Makes sense, it does have an EDM 700, perhaps it's worth trying to pull the data off of that?
 
Yes, pull the data! It’s very easy to do, per the manual. The hard part is getting the right application to read it, as I’ve heard there are issues with that, but your A&P should have that capability. Include yourself in the data review, it’s educational. Compare the flight data to previous flights. You don’t know how long those things remained in place.

Additional things to consider. I second the thought of not renting to this pilot again. That’s just pure neglect to properly conduct an even basic preflight. I would also have that pilot cover the cost of all repairs, if you are on the fence about it. Consider reviewing your checkout procedures to confirm they are sound and that your CFI or you are covering details. Like the Archer doesn’t have cute, soft, red-colored engine air inlets as an option.
 
I have done it twice, left the plugs in during start up. Both times the rope holding them together tossed them clear of the airplane luckily. Once was with my instructor on a 10° morning and he was rushing me. The plane had to be put inside to melt the frost off of the wings and we then pulled it outside, we were in a hurry to get the engine running for heat.
Second time was my own plane when I was rushing to get going to fly a 2 ship with my friend.
Now I don't rush anymore and always remove them in the hangar in the same order during my pre flight every time. Never deviate from my routine any more.

Sorry to see that, hopefully your plane is OK?
 
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My predecessor left the plugs in our King Air 200 once. They got sucked deep into the rearward part of the air intake. A few flights later he took off with the pitot covers on. Allegedly…in Minecraft I mean.
 
Gary Ward said:
I have done it twice, left the plugs in during start up. Both times the rope holding them together tossed them clear of the airplane luckily. Once was with my instructor on a 10° morning and he was rushing me as the plane was inside letting the frost melt off the wings and we pulled it outside and we were in a hurry to get the engine running for heat.
Second time was my own plane when I was rushing to get going to fly a 2 ship with my friend.
Now I don't rush anymore and always remove them in the hangar in the same order during my pre flight every time. Never deviate from my routine any more.

Sorry to see that, hopefully your plane is OK?
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It's crazy how far they will get thrown. I skipped a checklist on the Comanche once. I had landed, put the plugs in, and then realized I "stole" a tiedown spot. So I went to move it one spot over. Hopped back in to taxi it, and as soon as the blade caught, that cowl plug launched about 200'.
 
The “final walk around” habit just before jumping into the plane to start has saved a lot of pilots embarrassment, grief, and dollars. When I was a new pilot and not into this habit I started a single-engine plane with the hand held tow bar attached to the nose gear and taxied from one spot to another on the ramp. I was lucky the bar didn’t pop up into the prop.
 
TrueCourse said:
The “final walk around” habit just before jumping into the plane to start has saved a lot of pilots embarrassment, grief, and dollars. When I was a new pilot and not into this habit I started a single-engine plane with the hand held tow bar attached to the nose gear and taxied from one spot to another on the ramp. I was lucky the bar didn’t pop up into the prop.
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It's not a real pre-flight without the final walk around. Easy to get distracted with some of the basic preflight items - kind of like MIFS - only takes a minute or two - saved me on more than one occasion.
 
techflight said:
Got it, thank you so much for the input!

These cowl plugs were connected by a strap, completely agree ideally the strap would go over a blade but I can't control how each person who uses the airplane positions the strap unfortunately.
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It is a good thing to emphasize when checking out pilots in your planes, that that is the reason they have a strap.
I only watched them thrown out once. Was flying with a pilot and she taxied it to the FBO parking to meet me. We went out to the airplane to fly and on start up I watched the cowl plugs go flying.
I saw her taxi up but didn't see her put the cowl plugs back in after she got out, and she forgot she had done so.

I have also seen cowl plugs that have small flags sticking up so you can see them from the cockpit.
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Brian
CFIIG/ASEL
 
Well at least you could see the alternator belt. We had a local pilot do this to his own plane recently. He pulled them out and decided there was no damage and was about to go on a night flight. I asked if I could check his alternator belt with him. Turned out it had a big cut in it and would have probably failed on that flight.
 
I have foam plugs I use when I preheat. Left 'em in one time and caught it on taxi-out when the CHT's rose faster than expected.
 
I'd verify my renter agreement has liability provision on intentional or unintentional damage. Just like cars we rent. And make sure renter fully understands it.
 
Thanks for the input everyone, super helpful. To answer some questions:

Clip4 said:
You definitely want to pull the data.
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TrueCourse said:
Yes, pull the data! It’s very easy to do, per the manual. The hard part is getting the right application to read it, as I’ve heard there are issues with that, but your A&P should have that capability. Include yourself in the data review, it’s educational. Compare the flight data to previous flights. You don’t know how long those things remained in place.
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My maintenance shop unfortunately doesn't have an EDM PC interface cable, so I ordered one + a serial to USB adapter for my computer. I'll pull the data once it arrives next week. However, the mechanic doesn't seem too concerned. He says it could have been running hotter but given the amount of foam that was pushed through and on to the firewall, he believes there was still a lot of air flow.

Hang 4 said:
Mine have flags visible from the cockpit. Not idiot-proof, but so far good enough for this idiot.
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brcase said:
I have also seen cowl plugs that have small flags sticking up so you can see them from the cockpit.
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Yes, my next cowl plugs will definitely have the red flags visible from the cockpit! Funny thing is, I only bought these cowl plugs around a month ago and got the cheaper ones without the flag thinking who would be dumb enough to ignore the bright red plugs with the large "remove before flight" streamer, but alas...

TrueCourse said:
Additional things to consider. I second the thought of not renting to this pilot again. That’s just pure neglect to properly conduct an even basic preflight. I would also have that pilot cover the cost of all repairs, if you are on the fence about it. Consider reviewing your checkout procedures to confirm they are sound and that your CFI or you are covering details. Like the Archer doesn’t have cute, soft, red-colored engine air inlets as an option.
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Dmitry Buzolin said:
I'd verify my renter agreement has liability provision on intentional or unintentional damage. Just like cars we rent. And make sure renter fully understands it.
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I base my plane at a large flying club. I am not 100% sure how the liability works exactly, but they have assured me that I am not liable for any of the costs. It was near the 50 hour, but I believe the oil analysis is covered as well. We also have a safety office that will be dealing with the renter.
 
techflight said:
My maintenance shop unfortunately doesn't have an EDM PC interface cable, so I ordered one + a serial to USB adapter for my computer. I'll pull the data once it arrives next week. However, the mechanic doesn't seem too concerned. He says it could have been running hotter but given the amount of foam that was pushed through and on to the firewall, he believes there was still a lot of air flow.
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As a fellow Archer owner, I have to admit that this incident gives me great concern. I recently read somewhere of someone leaving their plugs in and, I believe, destroyed the engine. It is good that the foam remnants were pushed to the firewall, but how can anyone be sure that the high temperatures did not preceded the disintegration of the foam just by inspection. Some relief might occur if this happened on a cold day, but the best news would be the evidence provided by your engine monitor recording. I wonder if the oil analysis can give definitive evidence of any overcooking of the components, or oil itself.

I need to buy new plugs so I have the strap, long separated and shortened in my case, so it can be placed crossing a blade. It never occurred to me that strap was there for the safe expulsion, if forgotten. Dumb me, I thought it was there to keep all 3 plugs conveniently connected for insertion and removal.
 
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MajorTurbulence said:
As a fellow Archer owner, I have to admit that this incident gives me great concern. I recently read somewhere of someone leaving their plugs in and, I believe, destroyed the engine. It is good that the foam remnants were pushed to the firewall, but how can anyone be sure that the high temperatures did not preceded the disintegration of the foam just by inspection. Some relief might occur if this happened on a cold day, but the best news would be the evidence provided by your engine monitor recording. I wonder if the oil analysis can give definitive evidence of any overcooking of the components, or oil itself.
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Yes, I'm curious if the oil analysis can provide relatively definitive info on if I should be concerned about engine damage or not - if anyone has any additional insight here I would really appreciate it!
 
I had a renter take off with the towbar still on the nosewheel.

Someone called him and he landed. No signs of damage to prop or nose gear. Tow bar was buffed up a bit...
 
Saw where a socata took off and landed just as the cowling was burning up from leaving the plugs in.
 
It wasn't aviation related, but this happened at the start the 1999 Indianapolis 500. I was a crew member on another car at the time.

Scott Sharp, who qualified on the outside of the second row, suffered a humiliating gaffe when his pit crew neglected to remove the protective air blocks from the radiator inlets. The car pulled away from the grid with the air blocks still inserted, precipitating a swift and uncontrollable overheating condition.

Though the crew was able to get the car back out on the track, the damage was done, and the car dropped out short of the halfway point with transmission and engine failure. The incident prompted some teams across the grid to pay more attention to pre-race checklists and affix fluorescent "warning strips" or brightly-colored flags to the air blocks and other similar devices to avoid similar failures in the future.
 
I may be wrong but I'm pretty sure that any overheating concerns could be answered with a bore-scope. The discoloration of the cylinder walls, valves, or pistons etc would be fairly obvious. That and the oil analysis and a compression test should be able to solve that question in my mind.
 
Lindberg said:
What is the purpose of these things?
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Cowl plugs? This time of year, they help to keep birds out of the engine compartment. I remember seeing birds fly into the air inlets of a plane that was parked for maybe 15 minutes with nesting material.

I'm sure determined birds will find other ways into the engine compartment, and other places in the plane, but the cowl plugs help a lot. In winter, I suppose they help retain engine heat during a short stop or preheat, but otherwise they probably don't do much.
 
I use them for preheating in the winter. But I would think if I wrapped the strap around the prop and started the engine those plugs would tear up my cowling for sure.
 
So take your pick. Bird bird nests or the risk of still-installed inlet plugs to cook your engine. Sometimes things that are designed to fix a problem end up creating problems. Professional pilots have left jet engine inlet covers installed during a layover and destroyed a perfectly good and expensive jet engine during an engine start. That is also a lack of a good preflight as well communication breakdown between two crew members. Again, if you can’t see inlet plugs, especially those painted red, you shouldn’t have been flying that day.
 
What is the purpose of these things?
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In the winter, cowl plugs keep the engine warm ... while pre-heating before the trip starts, and on the ramp at a lunch stop.

In the spring, they prevent birds nests, as mentioned above.
 
Cap'n Jack said:
Cowl plugs? This time of year, they help to keep birds out of the engine compartment. I remember seeing birds fly into the air inlets of a plane that was parked for maybe 15 minutes with nesting material.
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I can’t imagine a bird nesting in a hot engine compartment, that’s a dumb bird and Darwin will hopefully prevent it from breeding.
 
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