Thanks to those who have sent me your data. Please keep them coming.Also - if you want to be anonymous please say so in the email. Otherwise I will assume you don't. ColynOn Jul 26, 2013, at 11:24 PM, Colyn Case wrote:Dear Hartzell/550 owners, If this email looks garbled to you, set your window as wide as you can. We've been having this discussion about a possible vibration problem but we haven't accumulated much data on the incidence of the problem or especially the incidence of a non-problem. To help us sort it out it would besuper helpful if everybody that has the 550/Hartzell combination could please add your information below. It is just as important to send your info if you DON't have a problem. (Please use the fixed width font and spaces not tabs). I volunteer to collect all the responses and publishthe result. If you would like to be anonymous you can send your information directly to me and I will remove your n-number and email before publishing. My email is colyncase@earthlink.net We have 1000 lancairs or so we think are flying and several hundred IV's with the 76" prop. It would be great to get a couple hundred responses. It would help even more if we could get this before or early into Oshkosh week. thanks in advance,Colyn n-number email lancair Hartzell prop part engine model I have symptoms of the model number discussed vibration issue (yes/no/not sure) N136CS colyncase@earthlink.net IV-P HC-H3YF-2UF/FC7693DF TSIO-550B not sure