Flap Rod

08-18-2009, 07:16 PM

Mike | Flap Rod

Correct me if I am wrong......

The existing flap extension rod is made out of stainless steel. 1/4" one end and 5/16" the other end.

Two years ago while doing some water work while landing; the flaps at 40* the starboard side flap rod broke at the flap end. A few days ago, flaps at 30*, hard landing, the port side flap rod broke at the flap end.

Are these rods designed to break when a large amount of water hits the flap or is this a problem?

If the rod is changed to a larger rod or larger rod ends; could this damage the flaps? The suggestion was to go to 3/8" and 3/8".

08-23-2009, 11:18 PM

jgrimaud | Flap Rod

I recently had a similar problem, hitting a high wave while landing, but the flap rod did not brake. The flap rod bent and the Flap hinge broke. The flap still worked, but fortunately I discovered it before another flight. The Flap Hinge was the one next to the fuselage and attached to the wind spar. This flap hinge has an obviously weak area where it is designed to go around the flap drive rod. If you had enough pressure to break the flap rod you probably should check in this area to insure the hinge is not cracked at this weakest point. (By the way a mike on my old flap rod indicated a constant 5/16 inch diameter.)

09-11-2009, 06:34 AM

Mike | Default

Was that 5/16 on both ends....?

09-28-2012, 11:08 PM

jar59nh | Flap weak point

I've been away from my project but I'm finally back a it. It's been good to read all the info & see all the names of Seawinders I miss.

I know his post was from a few years ago but I just want to mention a few things. As most are probably aware we had an accident early on that was caused by an undetected split flap after a water landing. That airplane was rebuilt but it had substantial damage from the cartwheel that ensued. Of course a good visual inspection of the flaps prior to takeoff should prevent any further accidents.

I've always felt that the current setup had two deficiencies. The first is that the flap is driven close to the hull where the wave action is greatest therefore the forces can break the rod ends or bend the rod. The second weakness is that we get our flap reading from the drive system and not the actual flap position. We have no 'cockpit' warning or indication of a split flap. Scott Devlon was working on a flap indicator that read the flap position of each flap. It's been a long time but I think he was using radio control servo sleeve and rods to follow the actual flap travel. A simple solution to reading actual control position.

Since I have not built my mixer/flap drive yet I am free to look at alternatives. I really don't like a system with at least 2 failure modes, electric and hydraulic. It just seems way too complicated for something as simple as putting flaps up and down. I want to drive the flaps from the center of the flaps with a cable and pulley system similar to Cessna 180's and all older Cessna's. If designed properly, they should even be lighter which would help our bloated Seawinds

Well that's my 2 cents worth.

Looking forward to seeing you at the next Splash-in!

John Ricciotti

08-16-2013, 11:18 AM

Larry Brunzlick | Missing hydraulic flap actuator bolt

I recently had a flap hydraulic actuator bolt come out and I think this is a first for this type of incident. It was coincident with another type of accident/incident that has been reported in the past.

A couple weeks ago I made a hard (bouncing) water landing with 30 degrees of flaps. I bent and broke the left push rod between the flap and the flap control arm. I haven’t had any trouble with 30 degrees in my limited experience, but I will probably only use 20 degrees from now on, or at least until I gain more experience.

I know that a broken push rod is not a new event for a Seawind, but here is what I found on further inspection. The right flap would not retract all the way. I discovered that the bolt holding the forward end of the hydraulic actuator was missing. I thought, wow! it must have sheared off. But I found the nut and bolt separately in the back and not damaged.

The bolt had come out with one of the two bronze bushings for the actuator clevis deformed and wedged on the bolt. The 5/16” nylon lock nut had apparently worked itself off and the bolt was in the process of working itself out. You can see from the picture how far out from the bushing that it had moved. The threaded end of the bolt was probable not even in the other side of the clevis because the threads were not damaged. If you look close you can see the deformity on the bushing caused by the hard impact and that’s when the bolt popped out.

I do not recall seeing any incidents of this nature, and needless to say I will be installing a drilled bolt and cotter key. The new bushing just came.

The bolt and nut are impossible to see without a mirror so routine scanning of the back compartment makes it difficult to detect this potential problem without getting your fingers up there.