Flap Track Replacement

[reecewallace]

I've been getting some play on my starboard flap while it's deployed and my mechanic says it's worn out (quick eye-ball). I can wiggle the flap and it has a decent amount of play vertically and a bit horizontally too.

I looked in the 170 parts catalog, but it's difficult to determine exactly what part # the tracks are. I'd like to replace all 4 of them with the 'thick' style according to my AME.

I'm guessing it's wise to replace the flap roller bearing systems simultaneously?

Can anyone help me with the part #s? My relationship with my mechanic is very self driven for finding parts which I enjoy, but it's a learning process every time.

Thanks.

[Bruce Fenstermacher]

Sure, what model of 170 do you own. All models are different.

But only 170B models have tracks. I've never seen a Cessna with flap tracks without play. Even new. The only way to know if they are shot is to measure them. Eyeball measuring is not accurate enough.

McFarlane is the source for these. The don't list 0523231-5 (from fig 3-56 and 8-46 in the IPC). You will have to call them. Rollers are fig 6-15 thru 20 and fig 11-15 thru 20and they are identical for each wing.

Here is 6-15 thru 20 only, 11-15 thru 20 is identical.

[daedaluscan]

McFarlane make a gauge, and most shops would have one I think?

My understanding is that this is a big job, with some wing skin removal?

https://www.cessnaflyer.org/maintenance ... ement.html

Do make sure that all the rollers are free and lubricated.

[reecewallace]

Sure, what model of 170 do you own. All models are different.

But only 170B models have tracks. I've never seen a Cessna with flap tracks without play. Even new. The only way to know if they are shot is to measure them. Eyeball measuring is not accurate enough.

McFarlane is the source for these. The don't list 0523231-5 (from fig 3-56 and 8-46 in the IPC). You will have to call them. Rollers are fig 6-15 thru 20 and fig 11-15 thru 20and they are identical for each wing.

Here is 6-15 thru 20 only, 11-15 thru 20 is identical.

Screen Shot 2021-05-28 at 6.09.36 AM.png

I have a 170B

[hilltop170]

Reece-
Having just gone thru the replacement of one complete flap track assembly on my 1958 C180, I can assure you it is not a simple operation, nor inexpensive. My right inboard original sandwich-style flap track broke on takeoff and jambed flap retraction so I just landed with two notches and no additional damage. My IA said if I had forced the handle down, it could have damaged the rear spar but as it was, the bracket was the only broken part.

He was amazingly efficient in replacing the entire flap track assembly. He had done half a dozen or so before so he knew just what had to be disassembled and how far to go with de-riveting the wing trailing edge. He also knew how to remove the flap and aileron cables without losing the rigging. The job took 12.5hrs labor for the one complete inboard track assembly replacement. The original sandwich-style Rib Assembly p/n1221010-7 has been superseded by the solid Rib Assembly p/n 1221010-15 on the C-180, and was $660 and in-stock at Cessna with 7 on hand. I bought mine thru Airpower in Arlington, Texas. Not sure if it is the same part on the 170B. Be sure and check that out.

I would have replaced both tracks on the right side but the outboard replacement would have required removal of the fiberglas Monarch aux tank in front of that track. Those aux tanks have been in place with ZERO issues since 1995 and I wasn't about to take a chance on creating any problems since the original outboard sandwich flap track is still in good condition. In reality, the inboard flap track failed because the lower attach angles where the track assembly rivets to the lower wing skin cracked and when it failed, the upward force of the flaps tried to peel the flap track up and away from the rear spar. The later style solid flap track assembly comes with an additional lower attach angle doubler that should prevent the flap track from failing. Cessna also sells that additional angle doubler as a separate part and I will be adding those doublers to the outboard track later. Additional inspection holes have to be installed before any access to the outboard track can be made.

As previously stated, do your due diligence in determining if you actually need to replace the tracks because of wear. They have to have a certain amount of play so the rollers can roll freely and can seem to have too much play if you don't know what to look for. Measure them to be certain.

In any case, if you feel you need to do something and the tracks are not worn out, add those lower flap track angle doublers and the original sandwich flap tracks should never fail like mine did. Another easy thing to do is remove the flap track rollers and inspect the rollers for distress. There are tiny needle bearings inside the rollers and if they are ok, grease them with waterproof grease and reinstall. Be careful to get the washers and bushings in the correct places on reassembly. If the rollers are seized or not turning for any reason, they will quickly wear out the track if they are skidding along the tracks, they must turn freely. A new replacement roller kit from McFarlane is about $435. WOW!

Another tidbit, the McFarlane “solid replacement tracks" are just the track itself (not the whole Rib Assembly that includes the track) and will not work on the original early-style sandwich flap tracks, they only work on the later style solid tracks. McFarlane also makes a replacement track for the sandwich flap tracks. The best I can tell, the correct part number for the 170B is MC0523231-14 but check the McFarlane website to make sure if you have to replace your’s because of wear. Again, it is the track insert only, not the entire assembly.

Good luck and post your final actions on your flaps, lots of other B-model owners are probably in the same boat.

[c170b53]

Well what do you know, I actually have a track gauge Reece. Once the travel restriction is lifted you’re welcome to fly over to YPK and I’ll give your machine an eyeball if you wish.

[Metal Master]

(This comment does not address the flap tracks them selves but rather the flaps). Any inspection of the flap installation of any Cessna flap tracks and rollers should include an inspection of the flaps themselves and the wear that can occur on the flaps per Cessna SEB95-3 R1. Single Engine Service Bulletin SEB95-3 Revision 1, Flap Support Inspection And Roller Washer Installation. A copy of this SEB can be found on McFalane's catalog associated with there replacement flap track rollers. The 1982 Cessna 182P I performed the annual on the first part of this year had heavy wear in the area of concern. The rental fleet I used to maintain of 30 single engine Cessna aircraft all 1979 and newer all showed the wear that this SB addresses. About half or better of these aircraft required replacement of the flap track brackets requiring partial disassembly of the flaps themselves. The rest all required the blending described in the SEB.
here is a link to the SEB from Cessna's support website.
https://support.cessna.com/custsupt/con ... s_id=22250
Jim

[c170b53]

Absolutely correct Jim, easily accomplished, the wear washers prevent the roller sides from boring a hole in the flap arms. Its the first thing I look at (along with whether the rudder pedals have straight axes) when someone brings their plane over for something. Tells me right away whether its been in good hands.

[Hineywheel Bill]

Too bad that there is not a replaceable wear surface inside the track so that it could be replaced instead of the entire part. Things are just not always as simple as they could be I suppose...

[hilltop170]

Bill-
McFarlane does make an insert for the sandwich style flap brackets. The following is buried in my post above;

McFarlane also makes a replacement track for the sandwich flap tracks. The best I can tell, the correct part number for the 170B is MC0523231-14 but check the McFarlane website to make sure if you have to replace your’s because of wear. Again, it is the track insert only, not the entire assembly.

[Hineywheel Bill]

Bill-
McFarlane does make an insert for the sandwich style flap brackets. The following is buried in my post above;

McFarlane also makes a replacement track for the sandwich flap tracks. The best I can tell, the correct part number for the 170B is MC0523231-14 but check the McFarlane website to make sure if you have to replace your’s because of wear. Again, it is the track insert only, not the entire assembly.

Ah ha, very good. I read your post but apparently I didn't let that part sink in.

[Globalpilot]

Hi Reece,


We are currently just starting the replacement of all four of my flap tracks on our 170B.

The part number for the flap tracks your looking for are by McFarlane part # MC0523231-14 and the Flap roller Kit is FLP-KT-1.

https://www.mcfarlaneaviation.com/produ ... 523231-14/
https://www.aircraftspruce.com/catalog/ ... ey=4410342

They are a litter cheaper from Aircraft Spruce.

We are trying to figure out if this can be done as the McFarlane instructions state by "Only" drilling our the trailing edge rivets in the flap well and lowering the flap well skin to gain access to the sandwich bracket rivets. In doing only the aft trailing edge rivets the flap well skin will not lower below the bracket itself.

Information on this process is not readily available on the web so far as I have found. Does anyone have video or pictures of the tracks being relpaced?

[IA DPE]

John:

Please take lots of pictures and notes so that when your project is complete you can write an article for the 170 News for posterity.

[hilltop170]

John, there are two, let’s call them z-brackets, on either side of the flap track that rivet to the flap well skin with 4rivets per track. If you drill out the trailing edge skin and those z-bracket rivets, the flap well skin should deflect down out of the way nicely allowing access to the tracks.

[Globalpilot]

Hi Richard,

Thanks for the information, although we have already removed the rivets from the "Z Brackets" the flap well skin will not pull down past the flap track horn without cutting the flap well skin

We have decided the cleanest way to accomplish this is to remove the front and/or bottom rivets of the flap well and completely remove it for access.

Pics added.