PIPER PA28-140 SPINNER question

[AviatorVette]

Hi guys, basically I did a night cross country yesterday.. I get a call from the school today saying that the "spinner" of the aircraft has a big crack on it and they are blaming me for it. They claim I pulled the plane by the spinner ( which i didnt ) I obviously know how to push back a plane.. The owner of the school says that since I flew the plane last and didnt "squawk" it, I am automatically at fault. Honestly I didnt see any crack on the spinner after flying / before. The owner doesnt listen to what I have to say and is blaming me for the damage. He says I have to pay $1000 USD for the new spinner. This school is located in camarillo. Anyone have any idea how I can get out of this situation ? Can anyone also list me the price of a spinner for pa28.. Thanks

[gttocatch]

get someone to repair it.Stop drill the crack and manufacture a patch.cheaper that buying a new most likely

[AviatorVette]

OK heres a link guys

COMPOSITE SPINNERS<br> FOR PIPERS & CESSNA'S from Aircraft Spruce (http://www.aircraftspruce.com/catalog/appages/pipersp.php)

It says that metal spinners often crack after 200-300 hours, now if there is a way for me to prove that the aircraft had a metal spinner and not a composite spinner, I may have a case here. He probably will still want me to pay the amount, I will say that I will pay only for a metal spinner and not a composite spinner which costs $800++

Do the maintainance logs of an aircraft list the type of spinners used? I am going to have to check it out then.

[SNS3Guppy]

Aviatorvette,

Spinners don't crack from ground handling. That is, if you pulled the airplane by the propeller, it wouldn't crack the spinner. It's possible to bend the back plate by pushing on the spinner, but even if that occurred, you wouldn't likely have seen cracks on your flight.

Without seeing the spinner and knowing where the crack originated or what exactly the owner of the flying club is talking about, it's very hard to discuss in detail the cracked spinner. However, most commonly they crack because they're improperly installed.

A thousand bucks is steep. You can get an STC fiberglass spinner for the same airplane, which will outlast the metal one, for about seven or eight hundred bucks. If it's just the spinner dome, it's about three hundred bucks

http://www.aircraftspruce.com/pdf/2008Individual/Cat08180.pdf

COMPOSITE SPINNERS<br> FOR PIPERS & CESSNA'S from Aircraft Spruce (http://www.aircraftspruce.com/catalog/appages/pipersp.php)

HOWEVER, don't ever fly with that operation again. The owner of the flying club has no business at all trying to throw that cost at you. I'd tell everyone you know to stay away from that place. Things break in airplanes, and airplanes are expensive. If the owner doesn't understand this, then he has no business being...in business.

You'll note the commentary in the Aircraft Spruce catalog cited above that it's not uncommon to see a spinner failure within a few hundred hours on something like a Cherokee. While that may be a bit of a stretch, as I've often seen spinners go the life of the engine, it's also true to an extent...a cracked spinner or back plate (bulkhead) isn't at all uncommon, either.

WagAero has the spinner for about three hundred fifty in aluminum...and that's the whole assembly, back plate and all.

Wag-Aero Online Store - September 2009 (http://store.wagaero.com/index.php?cPath=190_191)

It would seem the owner of the aircraft or flying club doesn't have a clue, and is making an effort to rip you off. don't let him do that.

Cracks originate in one of three places on spinners. The back plate itself, an attach screw hole, or in the smallest radius of the propeller cut-out. Often it can be something as simple as a scratch that caused it, or a little nick. It's called a stress riser, or a point at which the stresses on the part become concentrated, and eventually the part fails. It may be that someone overtorqued the attach screws, or failed to use plastic washers under them and instead used metal washers on an aluminum spinner. I've even seen people do boneheaded things such as use lock washers under the screws...guarantees a failure.

People frequently slip with a screwdriver while attaching or removing the spinner. They gouge or scratch the spinner, and there's a stress riser, waiting to crack.

When spinners crack, it's not uncommon for them to come apart under the stresses of operation, and leave the aircraft entirely or in part (the latter usually causing a lot of vibration).

I certainly wouldn't cough up a thousand dollars to pay the individual who's demanded it. I don't think he has a right to do so, but then you'll have to look at the policies at the place you fly. Unless he can show that you damaged it, then he should pay for it as an operational expense. You need to be able to look at the spinner and see what crack he's talking about, the size, nature of the crack, where it originated, etc.

You asked about "getting out of this situation." That's easy. The school is making an unreasonable demand. Don't pay it. Refuse. Fly elsewhere. If a school pulled something like that on me, I'd be out of there so fast the wake turbulence would rock the airplanes behind me.

You indicated that you didn't see a crack in the spinner after the flight. Did you post-flight the airplane? Most pilots, especially renters, don't. A post flight should be every bit as thorough as the preflight (and the preflight should always be very, very thorough...treat it like your life depends on it, because it does).

Whether you squawked the item or not is really irrelevant. Had you squawked the item, how would that be any different than not squawking it? If the school believes you damage the airplane, squawking the damage doesn't make it less damaged...therefore the argument by the school that you're responsible because you didn't write it up is meaningless and irrelevant.

The argument that it showed up after your flight is also largely without merit. If it happened during the flight and the spinner didn't come off...of course it's going to be seen after the flight. If not you, then the next guy. Chances are that if it did break on your watch,then it could just as easily have broken during the previous flight with the last guy, or it could have waited until a week later and failed on someone else. It's an airplane. Parts do break, cracks do develop, and that's life.

To be quite honest, if you're sure you did nothing to that spinner (and save for pushing really hard on the spinner, repeatedly, over time, it's very, very unlikely that you did anything to cause cracking...the owner is an idiot and should be blown off.

Does your school have a damage waiver or language in the rental agreement/contract which specifies who pays for what, and how much? The school owner is trying to grossly overcharge you, but even if you do end up agreeing to pay a portion of the cost (at this stage, there's no way I'd consider paying for it), check the documents to find out just how much in dollars and percentage of cost is applicable to you. Don't let this guy walk all over you. See if you can get some photos of the spinner.

[AviatorVette]

Hi thank you for your great reply, It was really helpful. The problem is I cant change school because they have taken the fee for the entire course in advance, I am about to start my commercial training soon.. If I want to quit there is a fine of $3000.... I made a big mistake joining this school but I cant help it now... Anyways here are the pics

http://i30.tinypic.com/4v4l8w.jpg

http://i32.tinypic.com/2r59p3l.jpg

[SNS3Guppy]

I'd stop right now and get an attorney to investigate your contract with the school. Their actions at this juncture are dishonest, and one should never pay up front. The recent collapse of Silver State Helicopters in which students lost an average of 50,000 dollars each is a good example of a long line of flight schools which have done the same thing. There's likely ample precedent to support you if you want to withdraw without a penalty. The collapse at Silver State has literally shut down the flight training finance available in the US. There's very little humor left for schools which do what silver state did...and the school you describe is doing what silver state did.

Even if you had put your fingers inside the spinner to pull the airplane, the damage that's evident wouldn't have occurred...and certainly not from pushing on it, either. Given that it's nearly impossible to pull the airplane with your fingertips inside the spinner...the school's claim that you damaged their aircraft in the manner they discribed simply doesn't hold water.

The inside of the spinner will need to be examined for more information, and a close-up examination will help reveal the nature of the cracking, it's origin, and what's cracked since it first started. Clearly it's easy to spot on a preflight or post flight. Again, whether you noted after the flight or not is really irrelevant to the claim of whether you caused it. The school is going to have to come up with a far better claim than they're presently making, however, to suggest that you're responsible.

Have you looked at your training contract or rental agreement to see where your responsibilities lie?

If you're a member of AOPA and have their legal plan, this is a good time to invoke it's offerings. If you're not a member of AOPA, now is a good time to join, and invest in the minimal cost for a legal plan.

The path of the crack around the screw in the same stress pattern created by the screw, intrigues me.

[bellsux]

Don't pay them.. just because you were last to fly it doesn't mean that it is your fault. What happens when a plane goes in for a 100 hr inspection? With their reasoning no one would want to fly the 99th hour as it would be a pretty expensive exercise.

Don't admit fault or liability but them to put down in writing their demands and get them to answer the following questions.

What is the part number of the spinner and backing plate.
Is it an OEM or PMA part.
Also ask them how often they dynamically balance the propeller and supply recorded references to the work carried out.
What torque was applied to the screw on installation and can you see the calibration records for the torque wrench.
Who was the person that put it on last and what date and time it occurred.
What is the part number of the screw and what approval are they using to use stainless steel hardware.

This will get them off your back. If not tell the local FAA inspectors as well...

[AviatorVette]

Thanks for your help guys, I went to the hangar today to check the maintainance logs for the aircraft and the mechanic wasnt available so I will have to go back tomorrow.. I will make sure to get all the details and will find out if it is a metal / composite spinner.. I do not want to pay any amount.. I have my instrument checkride in a few days and I honestly dont want to deal with all this nonsense from the owner.. I am really not able to focus on what I should be doing right now. I will try to sort it out soon. Another thing that is happening in our school is that we are not being reimbursed for our fuel, checkride, TSA clearances, written exams .. I am paying for all this out of my own pocket.. They say that they will add this to my "credit" and repay me at the end of the course.

[SNS3Guppy]

TSA clearances...there's some important insight. You're a foreign student?

The school is using that and holding it over you, right? I think the picture is becoming clearer.

[Fark'n'ell]

AviatorVette

If you look at the top of the crack there is a small amount of paint that appears to have lifted.Note the irregular shape of the two holes within that area.Looks like corrision and has been there for some considerable time.
Is it possible to get a closer photo of said area? Get an independant engineer to examine the spinner.Even if you had pushed on the spinner it would not have caused the crack unless there was an existing defect.
Good luck,
Fark

[mad_jock]

Even from that photo you can see that there is some slow crack propagation followed by fast fracture cracking.

And the point where the cracking started is right at the stress concentration point. If you get right in close and look at the metal it will appear dull and possibly ringed at the bit with the paint off and long bright strips in the other fast fracture bits.

Any materials engineer will take less than thirty seconds to tell them its a fatigue failure. If it was done by miss handling I would expect to see plastic deformation of the surrounding material. And as I presume its made out of 3mm alloy you could hanging the plane off a strip of it with out braking it. If you had pushed and pulled it it would have broken at mounting points.

You need to look up words like ductile tearing and fast fracture.

[SNS3Guppy]

Actually the photo doesn't tell you a lot. The underlying structure needs to be examined. The cracking may have originated from the support brackets behind the structure, external impact, or other areas or causes...that picture doesn't tell you nearly enough to make a judgment as to what has occurred.

[Von Klinkerhoffen]

To me , it looks like the spinner attachment bracket , visible in the top picture on the backplate , just below the prop leading edge where the 2 rivet tails are , has failed ! Centrifugal force has tried to pull that part of the spinner outward . Of course it can't move because of the screw at the front bulkhead , so the screw edge has acted as a stress raiser causing the crack to propogate from it , as you can see . From memory , the brackets are steel and are known to fail . If so , exaimine the edge of the break . If its nice and clean and grey/silver , its a fresh break . If it shows a dirty red/brown edge for most of its length with only a small clean grey section , the crack was pre-existing and only failed once at a critical length . Either way , there is nothing you could have done to cause this , tell him to take a hike !

[mad_jock]

SNS3Guppy as a ex mech eng it does tell you alot.

The intial crack is just outside the area of workhardening where they have folded the lip round just where the metal will have thinned due to stretching to form the lipped smoothed edge.And its bang on the stress concentration. Also its following the stress lines

A very simple example is shown below with a plate with a hole in it. Rotate it round by 90deg to get this case.

http://www.me.cmu.edu/academics/courses/NSF_Edu_Proj/StrAnalysis_ANSYS/figures/pb3-7/3.1RefineMeshVonMisses.jpg

The actual model would be way more complicated because its thin plate and quite a complex 3D load it would be non linear as hell. I suspect if they have done any Finite element analysis on it they have fallen into the trap that they have done a linear model on it and ignored variations in loads due to changing airspeeds and engine loads.

What also gives me an indication that it was a fatigue crack followed by fast fracture is the fact that the paint has been blown off the intial crack. When the crack does propagate until the critical crack intensity is reached when it does go the crack extends at the speed of sound in the material. The sonic pulse radiates from the crack tip and because the material around the original crack can move out of plane of the rest of the body and vibrates in the (in this case radial plane) it pings the paint off because it is quite brittle.

And after looking at one today I would agree with the poster above that the bracket has failed on the base plate causing the failure.

[AviatorVette]

Hi guys thank you for the extremely valuable information provided, I managed to convince the owner that I am not at fault. He said that if I could get the spinner assembly for $350 like I said, I wouldnt have to pay anything...

so from the link SNS3gupy provided this is what I could find

Wag-Aero Online Store - Composite Spinner Only for Piper PA-28-140 FAA/PMA'd (http://store.wagaero.com/product_info.php?products_id=2972)

that is only the spinner, do you know if the plate assmebly / bulkhead is provided too?

It is a PA 28-140

[Von Klinkerhoffen]

The power of pprune !

AviatorVette , are you expected to fit it for him too := ? You have done more than is required of you as a customer , you've pointed his nose in the right direction , now let him get on with fixing his plane ! He can start by calling the customer service number and getting advice on how to treat his customers first :} ! Then asking if it they can supply a backplate and front bulkhead . Do not part with any money yourself :ok: .

VK