Sport Pilot Talk

I was inspecting the Warp Drive propeller on my Sky Arrow yesterday, and I found two things...


1) One of the nuts on the backing plate for the spinner is stripped. I don't know if that's a Warp Drive part. For now, I just installed a nut over the nut plate. Would that tiny bit of extra weight so close to the hub cause a balance problem?

2) I noticed that one of the leading edge strips is just a tiny bit loose, as seen in this video:

http://www.youtube.com/watch?v=5JyWmc5Lh2M

Anyone know the recommended repair? I did just email Warp Drive and I'll let you know what they say

Thanks in advance - over 4+ years the prop has been trouble-free to this point.

Hi Eddie,

I posted an answer for you on the www.ctflier.com forum.

Thanks, Roger - got it.

I'll post an update both places in the morning.

Here's the result of yesterday's calls.

As I said, I thought I had emailed the video to Warp Drive. I had Googled "Warp Drive Prop" and the first hit is warpdriveprops.com and had sent it to their online email link and that was who I called first.

Turns out this is just a dealer, not the factory. The fellow's advice was that it should be a simple fix with epoxy, and that the weight of the nut should not matter.

I then called the factory (warpdriveinc.com). Spoke to a fellow there and he initially also said epoxy or SuperGlue. I then sent him the video (the other had actually gone to the dealer). On seeing the entire strip move, he said epoxy would still be a satisfactory temporary repair, but that if that was happening they'd really like to take a look. He said a whole new strip, bonded properly, would probably be less than $100. He said he did not feel it was a safety of flight issue, and that even if the entire strip departed the prop, the imbalance would be noticeable, but not dangerous. Oh, and he agreed the weight of the nut was not an issue.

Long story short, being a proponent of "Most Conservative Action", I'm going to go ahead and send all three blades to the factory for inspection/repair. I'm down for my annual anyway, so the timing is good, and he said they could turn them around in a few days.

I'm all for the cautious approach, Eddie - good for you! I'd be curious to hear what the factory says, as I'm considering upgrading my Woodcomp prop to a Warpdrive.

Paul,

Why change from Woodcomp to Warp? Just curious.

Dave, Evektor has gone to the Warp on its new SportStar and Harmony models. The factory seems to consider the Warp more robust, and given its nickel leading edge, I tend to concur. I've had to do quite a few epoxy repairs to my Woodcomp. They have not been difficult, and so far my prop is still serviceable and airworthy. But once it reaches the end of its useful life, it would seem to me reasonable to swap it out for the Warp, at about the same cost as a set of replacement Woodcomp blades. No LOA is necessary, since the Warp is used on new SportStars, and called out in the parts catalog.

That's my thinking at this point. I plan to keep an open mind for now, and gather input from folks like Roger and Eddie who have some experience with the Warp.

Hi Paul,

Since your plane didn't come with a Warp you will need an LOA to change props from what originally came on the plane with an SLSA, even if the factory now uses them. Your plane was not given its airworthy cert. with a Warp so you need permission to change. That said the factory should issue one without any issues.
Just because your aircraft Mfg is quick to switch I wouldn't be. Mfg do make mistakes as we all know and I have pointed out many to different Mfg's to fix. Sometimes they make decisions without getting all the research done and looking at long time field use.
I have flown a Warp for years. Because of that and now being a Repair Center for Rotax and comparing side by side and doing the maint. I wouldn't use a nickel edge Warp on my plane. I just tested 5 different Sensenich props against 3 other props (Warp, Neuform 2 blade and Neuform 3 blade). I now have a much lighter and easier on the gearbox Sensenich 68" on my plane. It does out climb my old Warp. Top speed for a 5600 rpm WOT was about the same. I just got through sending the results back to Sensenich. Warp is fairly popular because of a much lower price than some. It will hold up if a small stone hits it better than some composites, but if you do hit something substantial it will absolutely transfer more energy into the gearbox and crank. There is a very good chance you will bend the prop shaft and or prop flange. It will also bang and clunk more during starts and stops due to its solid heavier weight.
There are some good props out there. The Sensenich I have right now is a light composite with a metal edge. The up side is if I hit something substantial there will be a lot less energy to my system and not near as likely to trash the prop shaft. The metal edge will still protect my blades.

Don't get me wrong. I do like the Warp and it served me well, but after all these years I think with the new technology there is something better for the end user.
Will the Warp work and fly, yes.

Thanks, Roger. As usual, you've given me a lot to think about.

Update...

The factory received the blades and the leading edge rebonding should be straightforward.

Darryl gave me permission to post his earlier email to me:

Hi Ed,

Thanks for the form. I will watch for the blades to arrive and start the work on them right away. As far as the blades with or without the nickel edges this will make no difference whatsoever on the gearbox. With the diameter of propeller you have, the light weight hub and the tapered tip profile we are so far under the allowable limits of the Rotax box there is no reason to question the nickel edges due to weight. A new set of blades just like what you have sells for $885.00 or $705.00 without the nickel. Trading your set of blades in would drop this cost about in half or we can repair your blades for around the $100.00 range based on what you have described.

With the holidays, it may be a week or so before they're done. I OK'd the repair, and they said they'd also inspect, refinish and balance all three blades as part of the repair.

I'll report back with photos when I get them back.

Interesting, Eddie. They quoted me $965 for three blades with nickel leading edge. That was for 68" diameter -- I don't know the size of yours. But it sounds as though repairing the existing ones is a bargain.

roger lee wrote:Since your plane didn't come with a Warp you will need an LOA to change props from what originally came on the plane with an SLSA, even if the factory now uses them.

Roger,
I am under the impression that, if there is an optional Service Bulletin covering a part substitution, an LOA is not required. Is this also your understanding?

Hi Paul,

The key word is "substitute" verses option. If it is just an option then you would need an LOA for just your plane because it isn't original equipment. If the Mfg published an SB and stated that it was now substituting the Warp for the original then you are right it doesn't need an LOA because they are addressing the fleet and saying the original is now being replaced by the Warp and they are giving it a fleet approval. I have filed several fleet approval letters instead of just a single LOA. Then the MGF publishes it's fleet approval which usually has a number that addresses everyone with that plane. Then it only becomes a logbook entry and a reference to the fleet approval letter.

Eureka!

We mounted the blades at 22º, one less than before, looking for an extra 200 rpm in the takeoff and climb.

Sure enough, right to 5,200 rpm on takeoff and throughout the climb, when before I barely saw 5,000 rpm, if that:



That was taken shortly after takeoff, before retracting takeoff flaps,

I climbed to 9,500', showing 5,200 rpm all the way up. Full throttle and level at 9,500, I saw about 5,500 rpm and about 102k TAS:



This is a knot or two better than I used to get at full power when I'd see about 5,100 or 5,200 rpm and about 98 or 99k. It remains to be seen what effect this all has on fuel consumption. At other altitudes, I was going a tad slower at any given rpm, which makes sense with less pitch.

Overall, I'm very happy so far.