Why we do preflight inspections

[BruceAir]

The bad news is, I didn't get to go flying today. The good news is, I didn't get to go flying today.

Among the many things I love about the Beech A36 is the fact that you can open the cowling and really look at the engine during the preflight inspection.

This morning I was scheduled with a student for recurrent training in the Bonanza. We ran through the cockpit checks, flagged down the fuel truck, and started the exterior inspection. We wiggled and poked all the stuff on the right side of the fuselage, the empennage, the left flap and landing gear, and the remainder of the left wing. Then we opened the left side of the cowling.

All the usual items appeared OK--brake fluid, rubber grommets on the fuel-injector lines, oil filter safety wire, etc. But then we noticed a piece of gold-colored machined metal peeking from the baffling, where nothing should be sticking out. We extracted the 6-inch shiny thing and quickly discovered that it had once been half of a cross-brace on the front side of the oil cooler.

I had flown the airplane a few days ago (with an FAA test pilot who uses some of his proficiency budget to stay current in the Bonanza), and we noted no discrepancies on preflight or during our flight, which involved air work, a couple of GPS approaches (the Garmin GNS 530 is one marvelous piece of equipment, by the way), and some simulated engine-out landings (a fun exercise in the A36). A couple of other people had flown the airplane in the interim, so I don't know when the piece finally snapped.

You'd probably never spot this sort of thing peering through the oil-dipstick access door on a Cessna, and it certainly wouldn't have been visible by looking through the intakes. But regardless of how much you can see of an airplane during a preflight inspection, make sure you LOOK.

 

[The Old Man]

My preflight is more of what I don't (see or feel) than what I do.

Hopefully, I don't:
Feel excessive or growing play in aileron, rudder, stabilator, flaps.
See flat spots on the tires (tread or low pressure).
See junk in pitot tube or static ports.
Feel nicks or scratches on propellor blades.
See any wire, tube or hose dangling unconnected in the engine compartment. (I don't need to know where everything goes, I can figure out where a dangling one goes if it is the only thing dangling loose in that area.)
See any oil or other fluid spots on the inside bottom of the cowling.

The few things I DO check.
Safety wire on; air filter, alternator, oil filter and crancase drain plug.
Oil level.

The advantages of being sole owner/pilot.

 

[Lance F]

It's not just Cessnas that only have a oil filler peep hole to look into. Mooneys are that way too. Therefore I make it a point to remove the full cowlings top & bottom on a fairly regular basis. If you do this on a Saturday morning with all the other aiport junkies around, you get a lot of eyes checking things out and helping to find even the tiniest discrepancies.

 

[Dave Siciliano]

Bruce:

I'm sure with you on the Beechcraft. I'm also a sole owner, sole flier; so, I don't have to worry about what someone else may have done. But I still have to look for things that just happen. The worst I've found on a pre-flight is a safty wire broken on the back of the prop hub. When I do fly Cessna products, I'm very uncomfortable not being able to see the components you mention.

Then again, I was watching a Malibu owner pull the entire cowling off the other night. He found two fittings that had worked loose. In order to pull the full cowling off the Bo, I'd have to remove rivets. Since my plane is TN, it's very crowded under that cowling!!

Guess it's all relative.

Best,

Dave
A-36TN ADS

 

[poadeleted3]

So far on preflights I've found a busted flap mount, busted alternator mount, and twice now water in the fuel. If I've missed anything because of having to peer through a little oil door, it hasn't bitten me. Yet. Being able to open the cowl was something I liked about Warriors when I flew them, and it's something else I like about the Tigers.

 

[Richard]

BruceAir, good going. WRT the Cessna cowling I find it rather disconcerting I can't see the engine. On Pipers where I could open the cowl it would add maybe 20 minutes to my preflight. Unlike the Old Pilot from Plano I'd rather see the engine than feel it. I guess I just like looking at engines and perhaps I don't trust myself to correctly react by feel alone.

 

[The Old Man]

Richard,

I do "see" the engine. The mouse has great big doors on both side of the cowling. You can do an annual without removing the cowling, it is so open.

And I obviously do look in for those things I hope not to:
See any wire, tube or hose dangling unconnected in the engine compartment. (I don't need to know where everything goes, I can figure out where a dangling one goes if it is the only thing dangling loose in that area.)
See any oil or other fluid spots on the inside bottom of the cowling.

And see:
Safety wire on; air filter, alternator, oil filter and crancase drain plug.
Oil level.

 

[Toby]

And see:
Safety wire on; air filter, alternator, oil filter and crancase drain plug.

Where are those last two items located? Is the drain plug the little handle you pull up to allow some fuel to drain out the bottom? Also, I'm not sure if I've ever noticed safety wires -- how small are they, and where are they located?

 

[BruceAir]

http://www.chiefaircraft.com/Aircraft/OilSystem/Images/CH_48103.jpg

The safety wire runs through the little tabs arranged around the top and prevents the oil filter from backing off the screw-on fitting.

 

[poadeleted20]

...oil filter and crancase drain plug

Where are those last two items located?

In most cases, the oil filter (if there is one -- some engines have only the screen which you can't see without disassembling things, and which should have shorter oil change intervals) is mounted on the accessory gear case on the back of the engine. In some cases, the oil filter may be remotely mounted on the firewall with hoses to fittings on the back of the engine. In either case, it should look like the gizmo pictured above.

The crankcase oil drain is located on the bottom of the sump. In some cases, it's a real screw-in plug like you find on most cars, but in others it's a "quick drain" valve that merely needs to be rotated and pushed up to start the drain.

Is the drain plug the little handle you pull up to allow some fuel to drain out the bottom?

No -- you are thinking of the fuel strainer drain, which is something else completely, designed to allow any sediment or dirt caught in the fuel strainer to be drained before flight.

RANT ON

One of my real pet peeves is instructors who never show their students the inside of an engine compartment other than through the oil door hole. Any student who can't identify all the significant components in that compartment (lube, ignition, and electrical systems, all belts and pumps, etc.) shouldn't be allowed loose alone with an airplane. And any such student's instructor deserves a 709 ride on his/her CFI ticket.

RANT OFF

 

[EdFred]

RANT ON

One of my real pet peeves is instructors who never show their students the inside of an engine compartment other than through the oil door hole. Any student who can't identify all the significant components in that compartment (lube, ignition, and electrical systems, all belts and pumps, etc.) shouldn't be allowed loose alone with an airplane. And any such student's instructor deserves a 709 ride on his/her CFI ticket.

RANT OFF

Ron -

I was thinking the same thing. No fault of the student, of course, but it was done the same way with me when I was training in the Cessnas. Just look in the hole. On the Pipers we opened up or removed the cowl for preflight inspections. From working on cars - a 4 stroke piston engine is pretty much the same whether in a plane or car - and pretty easy to find anything. I am surprised at the lack of knowledge of what is under the cowl by some private pilots - but not blaming them for it.

 

[Terry Miller]

I don't know how this might apply to others, but this helped me a lot.

From the very first when I started flying again, I explained that I didn't just want to know how to fly the airplane. I wanted to know how the airplane flies. I wanted to know the make up and condition of the craft as much as possible. I requested and was granted permission to be involved every time the aircraft went OOC.

Oil change, 100 hour, packing wheel bearings, whatever. Any time they popped the hood, I wanted to be there. They were glad to have the gopher I guess because they let me be there for a lot if not all of work, including the annuals, 100 hour's, and any other maintenance that occurred. Even started paying me to be around after a while.

Looking at the parts is good, putting your hands on them is better. It was a good deal for both sides and I came away with a lot of information I could not have gathered any other way.

If you have an opportunity to do the same, I highly recommend it.

 

[bbchien]

Two years ago I was giving a 7 hours 2 day BFR to a returning pilot (20 years). I inspected the gear saddles (C172RG) and grounded the airplane. Good thing, too. Got a lot of flak for that, but the AD came out about 3 weeks later. Could'a been very expensive and potentially hurtful....NOT MR Popularity....

 

[The Old Man]

Where are those last two items located? Is the drain plug the little handle you pull up to allow some fuel to drain out the bottom? Also, I'm not sure if I've ever noticed safety wires -- how small are they, and where are they located?

As 'splained by others, ...
My oil filter is a cartridge type CFO100 on the back of the engine. The safety wire keeps the attaching nut from backing out as the nut should be just tight enough to stop it from leaking, nothing more. The drain plug referenced is a quick drain on the crankcase sump.

One of the nice things about your own plane is knowing where the items are and more particularly which way the safety wire was run. On my quick drain, If I can see the tag end of the wire behind the forward side of the plug, I know it hasn't moved. I know exactly where to look for the tag end of the filter safety wire.

 

[The Old Man]

I don't know how this might apply to others, but this helped me a lot.

From the very first when I started flying again, I explained that I didn't just want to know how to fly the airplane. I wanted to know how the airplane flies. I wanted to know the make up and condition of the craft as much as possible. I requested and was granted permission to be involved every time the aircraft went OOC.

Oil change, 100 hour, packing wheel bearings, whatever. Any time they popped the hood, I wanted to be there. They were glad to have the gopher I guess because they let me be there for a lot if not all of work, including the annuals, 100 hour's, and any other maintenance that occurred. Even started paying me to be around after a while.

Looking at the parts is good, putting your hands on them is better. It was a good deal for both sides and I came away with a lot of information I could not have gathered any other way.

If you have an opportunity to do the same, I highly recommend it.

I concur, but....
For preflight purposes, I don't need to check that the top wire from the left mag goes to #2 top plug, etc. Some of this is from having your own plane. I know that it was wired up right last time I flew it, so if all the wires go somewhere (no loose ends), then they are hooked up right.

 

[Terry Miller]

I concur, but....if all the wires go somewhere (no loose ends), then they are hooked up right.

Yes. Where I was at the time, I just wanted to know how many parts there were, what they were, where they were, what they do, etc. The foot bone's connected to the ankle bone kind of thing. I wanted to spend enough time under there to know if something looked 'wrong', what wrong looked like.

And, that info comes in handy when you sit down somewhere trouble shooting a sputtering engine or something similar.

I got that way after an engine quit for about a 4 second count one time in the past. We sat down and pulled the cowl. I knew then tho that unless there was a 'push this to fix it' button, I was pulling the cowl for no apparent reason.

 

[Maverick]

The following is not something that would normally be found during a pre-flight but it highlights a point. One of my friends who ran a flight school acquired a Mooney. On the first flight after taking delivery of the airplane he and the other pilot that was with him heard some clunking noises when they banked the airplane. The noise seemed to be coming from one of the wings so when they landed the started removing inspection plates and found a hammer laying inside the wing. now I don't know if he did a pre-purchase inspection or not but man what a surprise that would be.

I always give my airplane a very thorough look whenever I have work done or an annual done. I just hate to find things that were not put back together properly or screws missing. There is an air intake on the side of my cowling that is an air scoop for the oil cooler. Often times I get the airplane back with the rubber duct partially blocking the airflow to the oil cooler. That is now the very first thing I check anytime the cowling is removed for any reason and is a normal part of my pre-flight check.

Jean

 

[Lance F]

When we did the prebuy on my Mooney, we found a flashlight wedged inside the right wing. Maybe there's something about Mooneys that makes mechanics forget stuff in the wings.

 

[bbchien]

When we did the prebuy on my Mooney, we found a flashlight wedged inside the right wing. Maybe there's something about Mooneys that makes mechanics forget stuff in the wings.

"Take the cowlings off in my hangar. Put the fasteners in the jar. Do the work and return the aircraft to the hangar. I will inspect and re-cowl."

 

[Lawreston]

Ron -
I am surprised at the lack of knowledge of what is under the cowl by some private pilots - but not blaming them for it.

)) I was right out of the woods, perhaps my 2nd lesson, when the young CFI was having me identify parts visible(or not) through the COH(Cessna Oil Hole).
I got them all right and he continued, "Where's the radiator?" I, running on success, prepared to sh....................."Hey, no trick questions; this is air-cooled ." He just grinned and said, "Let's go flying."

HR

 

[woodstock]

preflights so far have been fine. runups on the other hand... I pulled the carb heat lever out onto my lap, once. oops.

 

[wsuffa]

"Take the cowlings off in my hangar. Put the fasteners in the jar. Do the work and return the aircraft to the hangar. I will inspect and re-cowl."

I learned this lesson when I found half a plastic oil container in the engine under the oil filter after an oil change. That was the drain pan when they removed the filter. I could see it without decowling. When we decowled, we also found a wrench in the engine compartment.

Never again will I accept it back without checking everything.

 

[gkainz]

Shops don't use a Tool Accountability Program in GA maintenance?

 

[poadeleted20]

)) I was right out of the woods, perhaps my 2nd lesson, when the young CFI was having me identify parts visible(or not) through the COH(Cessna Oil Hole). I got them all right and he continued, "Where's the radiator?" I, running on success, prepared to sh....................."Hey, no trick questions; this is air-cooled ." He just grinned and said, "Let's go flying."

No trick question indeed -- most Cessna singles (in fact, most all light GA singles) have a radiator, and in many, it's plainly visible if you look in the front air inlets. Yes, it cools the oil, not a dedicated engine coolant like "liquid-cooled" engines, but it is an important item providing a significant part of your engine's cooling budget in addition to the heat carried off the cylinder vanes, not to mention the fact that 90 psi leaks from the oil cooler can drain your oil system very, very quickly.

 

[ggroves]

RANT ON

One of my real pet peeves is instructors who never show their students the inside of an engine compartment other than through the oil door hole. Any student who can't identify all the significant components in that compartment (lube, ignition, and electrical systems, all belts and pumps, etc.) shouldn't be allowed loose alone with an airplane. And any such student's instructor deserves a 709 ride on his/her CFI ticket.

RANT OFF

Preach it brother..! I use my friends Cherokee 180 that parked on the ramp near the flight school. It is MUST KNOW information for every pilot.

Greg
CFII

 

[Anthony]

I found a birds nest in my Tiger a few months after I bought it. And it was in an area, you can't normally see, the lower nose bowl. I was replacing a landing light and noticed the pieces of straw. Not a pre-flight, but shows the benefit of doing basic maintenance and poking at your airplane once in a while. It could have easily caught fire in flight and ruined my whole day!

 

[poadeleted20]

Preach it brother..! I use my friends Cherokee 180 that parked on the ramp near the flight school. It is MUST KNOW information for every pilot.

Per a request from Adam, I have agreed to host a "show and tell" under the hood of my Cheeger at the Wings Field BBQ fly-in on Saturday, May 14 (no rain date for me as the 15th is Commencement at UMES and I gotta be there in my flat hat and bag). More details to come from Adam...

 

[Graueradler]

In the first annual after I bought my Cherokee, we found a mud dauber nest on top of the aileron balance weight so large that it did not allow full aileron travel. It would have been detectable on preflight if you knew what to look for. When pushing the aileron all the way down, the top of the wing tip would deflect where the nest was hitting it. There were also large nests loose inside of the wings and one behing the heater control flapper valve. Since then, I leave the plane parked with the flapper valve closed (Heat On).

 

[Graueradler]

Per a request from Adam, I have agreed to host a "show and tell" under the hood of my Cheeger at the Wings Field BBQ fly-in on Saturday, May 14 (no rain date for me as the 15th is Commencement at UMES and I gotta be there in my flat hat and bag). More details to come from Adam...

I was issued a "Flat Hat" when I joined the Navy in 1958 and never wore it in 8 yrs. I wonder if they are still issuing them.