The Value of a Good Pre-Flight Once in a While

Pilot Steve

Pilot Steve

Pre-takeoff checklist
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Pilot Steve
Some of us that have been flying for a long time can get in the habit of doing the two-minute aircraft inspection. I do. But even with a checklist pre-flight, I'm not sure I would have caught this issue unless I made it a point to examine the entire spinner.

Frankly, this was spotted by accident as the prop was being moved through by hand when looking at something else. It would have made for a bad day if the spinner crack had continued to spread and left the aircraft in flight.

I share this incident to help the newer pilots understand that you will get lazy in your pre-flight check as you fly more but every so often it is good to go back to basics.

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That would get exciting. Never lost a spinner but had a friend who did! Had to change his shorts.


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It's funny, though, how your eye gets drawn to little things that are not just right, even with a quick inspection. I spotted a rocker cover screw that had backed out a half-turn out of the blue during a recent pre-flight inspection. Don't know how that happened, but that little guy somehow just stood out like a sore thumb during the pre-flight engine inspection.

FYI, a spinner failure can be very exciting. I had the crappy plastic rear spinner bulkhead in my Traveler--which had undergone from the looks of the aftermath a thoroughly unapproved prior repair--which decided to crack through and fail during a post-annual takeoff. The failed spinner cocked and the imbalance prevented the application of full power due to excessive vibration. Fortunately, I was able to nurse the plane at partial power back to the runway for an emergency landing. The trashed spinner chewed up my front cowling a bit and destroyed itself, but otherwise no structural damage. I now have the improved and much sturdier metal rear bulkhead.
 
I dunno about the "once in a while" thing... I kinda believe in thorough preflight every time...

Notice, I also waffled. I said kinda.

Is it so hard, or inconvenient to do it every time... Maybe not necessary if you just stopped at an en route strip for a "compelling physiological need" with no need for gas or oil...

But, might not be a bad idea to at least kick the tires before we light the fire...

I'm really glad the op caught that cracked spinner... What'd you do about it?
 
I run my hand over any screws during my preflight. It was something I started doing years ago after fixing aircraft parts. You'd be amazed out how quickly your hand notices something you may not see easily. Pretty sure that method would've worked here too as the crack is fairly close to the screw area.
 
You guys might think this is wierd: I took a paint pen and put a mark on the trailing edge of each spinner screw so on pre-flight I can tell if anything is starting to back out. I’ve also got a front mounted elevator canard that is mounted to a special engine mount and I do the same with the canard mounting bolts.
 
Nice catch.

Human psychology being what it is, we must always be alert for “confirmation bias”. IOW, we really want to fly, and subconsciously don’t want to find anything getting in the way of that goal. And when we do find something marginal, we’re primed to think, “it’s probably OK”. Best solution is to go into the pre-flight with the mindset that something is wrong and it’s your job to find it.

Best catch I ever recall was a Cirrus owner that, looking at a sump drain, noticed it was safety-wired “the wrong way”. I doubt I ever would have caught that.
 
CharlieD3 said:
Maybe not necessary if you just stopped at an en route strip for a "compelling physiological need" with no need for gas or oil...
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Nope. Still necessary.

To skip one in a case like this is to assume that legs of a certain length or stops of a certain duration make the plane immune to problems that may have developed on those flights. I fail to see the logic there.
 
455 Bravo Uniform said:
You guys might think this is wierd: I took a paint pen and put a mark on the trailing edge of each spinner screw so on pre-flight I can tell if anything is starting to back out.
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Not weird at all.

As far as loose screws, I caught this on a preflight on my Sky Arrow:

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It’s a screw for an inspection plate on the elevator that had backed out enough to catch on the horizontal stabilizer. I caught it mainly because there was a “hitch” as I moved the elevator through it’s travel. Good news is I caught it. Bad news is it had probably been backing out for a while and I didn’t catch it earlier.
 
Bellanca_Pilot said:
That would get exciting. Never lost a spinner but had a friend who did! Had to change his shorts.
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Exciting how exactly? I've lost a spinner more than once. In each case it was a 'F*ck, the spinners gone, now we're going to have to down the plane until we can get it replaced' moment. And in each case that moment happened while standing on the ground in front of the plane post flight. Did not even notice in flight. Guess I was just lucky?

But I'll agree with preflight comments. Those cracks start small but they can get big in a hurry. Gotta look for them carefully every time you get ready to fly.
 
I think you were lucky.

A spinner getting flung off quickly would usually have little effect.

I think the horror stories are from a spinner just coming partially adrift, and the resulting imbalance causing MAJOR vibration.
 
I always do a thorough preflight on my Warrior before the first flight of the day. Takes about 15 minutes. I carry my personally developed laminated checklist, but have it memorized now.

Some of the things I do, that are a little unusual and have not made it onto the checklist yet:
- Run my hands over the spinner and touch each screw. I do this this because I once found a loose one.
- Pull the empennage access panel in the baggage area and use a flashlight to check control cables, ELT, and such.
- Bump the stabilizer along its long axis to ensure there is no play.
- Try to wiggle each spark plug and harness connection. Once found a loose harness connection. Once in a Nissan 240SX I had a spark plug blow out the top of the head. It dented the hood! While I'm in the engine compartment a flashlight aided look around for anything amiss.

I generally do not do such a thorough preflight if it is not the first flight of the day and I have not left the airport, such as a stop for lunch or fuel.
 
FastEddieB said:
A spinner getting flung off quickly would usually have little effect.
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From experience, I'm less worried about the spinner than I am about shattering another very expensive backplate assembly. That just adds to the pain.
 
Update: I decided to go with the TCB composite spinner. Currently at the paint shop.

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Then thing I really miss about my Cherokee was being able to quickly decowl the engine and have a close look. I found loose screws on more than one occasion. It takes a half hour to pull the fairings off my current ride, so I just don't do it. I think I do take a close enough look to see cracks in the spinner, though.
 
FastEddieB said:
And when we do find something marginal, we’re primed to think, “it’s probably OK”. Best solution is to go into the pre-flight with the mindset that something is wrong and it’s your job to find it.
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A corporate pilot friend of mine offered a great suggestion. He said when he finds something out of tolerance he phones another pilot friend to sense check it. He said, just talking it over makes him realize how stupid it would be to fly with the issue since he can't defend it. It is a policy I have adopted and has prevented me from having those idiot moments when we realize we never should have left the ground.
 
FastEddieB said:
I think you were lucky.

A spinner getting flung off quickly would usually have little effect.

I think the horror stories are from a spinner just coming partially adrift, and the resulting imbalance causing MAJOR vibration.
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I could see how a partial departure could cause an imbalance. But I don't think I was lucky in that sense. I strongly suspect that much more often than not, by the time they're to the point where they let go, they let go and depart almost instantly and the pilot has no idea it happened until after the flight. The thought of a spinner hanging on partially attached is definitely not something I'd ever loose sleep over.
 
Juliet Hotel said:
I could see how a partial departure could cause an imbalance. But I don't think I was lucky in that sense. I strongly suspect that much more often than not, by the time they're to the point where they let go, they let go and depart almost instantly and the pilot has no idea it happened until after the flight.
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Interesting.

I always assumed as a crack spread or screws loosened or whatever, there would be at least an initial phase of “partial departure”, as you put it, with its attendant vibration.

As an informal survey, maybe let’s hear from those who have partially or completely “lost” a spinner in flight. I’m also curious as to whether it did any subsidiary damage to the airframe or engine during said departure.
 
455 Bravo Uniform said:
Spinners are ridiculously expensive, aren’t they?
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Yes they are! When I was a partner in a 172, we had a cracked spinner that couldn’t be repaired, and also had to replace the rear bulkhead. $740.

Just for giggles, I checked the price of one for an RV-8. $210, with both bulkheads. So here I am a few years later with an -8. Buying a used Experimental brought with it its own set of problems, but at least factory parts are a lot less expensive.
 
FastEddieB said:
As an informal survey, maybe let’s hear from those who have partially or completely “lost” a spinner in flight. I’m also curious as to whether it did any subsidiary damage to the airframe or engine during said departure.
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I know I've lost at least two but three is the number that sticks in my mind. It was a long while back during my banner flying days and details like that can get fuzzy after a while. Never felt a blip in the air and no damage to the plane or prop. I don't think there any damage to the backer plates in any that happened on my watch but I could be mistaken about that.
 
Thanks!

My impression may be biased because we’re far more likely to hear the “horror stories” of spinner loss than benign examples such as yours.

Anyone else with stories to tell?
 
For those that have not had the pleasure, the biggest issue for me is not the spinner but the damage to the bulkhead assembly from imbalance when the spinner departs. The bulkhead assembly that holds the spinner on a 182 is crazy-expensive. That little dinner plate is currently $3,313 new. If anyone knows of an inexpensive yellow tag for part 0752637-1 or 0752637-27, please send me a DM.
 
ateamer said:
Just for giggles, I checked the price of one for an RV-8. $210, with both bulkheads. So here I am a few years later with an -8. Buying a used Experimental brought with it its own set of problems, but at least factory parts are a lot less expensive.
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Would you please consider starting a new thread discussing some of your experiences buying a used experimental? I'd like to hear your thoughts about it.
 
I treat every pre-flight as an occasion to get out of the house when my family is driving me nuts...; ) I visit the plane, do my thing and leave knowing I did a thorough pre-flight without the pressure of pre-flighting right before the flight. When and if I do find an issue, my flight isn't ruined. On flight day, I check the fuel sump again and off I go.
 
I try to take every inspection seriously. I've been in maintenance and maintenance support for years. Looking and seeing are two different things. I run my hand over the spinner fasteners, and along the leading edge of the prop blades. If there is a chunk missing or a significant nick you'll feel it snag your skin.

Years ago we had a BAE Jetstream J32 in the hangar for a 7 day inspection. One of the old timers worked it. He had eyes like fish hooks. He discovered there had been a lightning strike. It hit the prop and exited the trailing edge of the flap and near the tip of the vertical stab. Crews (and apparently passengers) were completely unaware. I remember standing right there looking at the prop blade and not seeing the strike until he pointed to it. It wasn't such a small thing. It looked like someone had taken a small bite out of the aluminum. It was my first exposure to the whole topic, but I never forgot it.

Also used to rent a DA-40 with a composite prop. It seemed to collect dings and dents, apparently all within limits. I did not like that composite prop. I started photographing the blades on each leg of my trip so I could tell if I was looking at new dents or the same damage I started with, and if it was getting worse from leg to leg. It never gave me any problem, but I prefer solid aluminum.
 
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