i have just printed my boarding passes for a ryan air flight and made a mistake . The last letter of my wifes sir name is an (s) in stead of an (a), do i need to contact ryanair to correct this

Yes. Definitely. Just to be sure. How long since you made the booking? If you do it immediately, they usually won't charge you. If you leave it too long, they will charge a fee. (Bitter experience) Contact them immediately...I don't understand why you asked here, when the people who CAN help you are a phonecall/email away???

i asked here as its such a minor error they wont even notice as all other details are correct passport number etc . I thought why draw there attention to it. I booked it in august and checked in on line today , fly next week.
How much would it cost to correct and can an error like that stop u flying ?

Yes, I thought the 'drawing attention' to the minor error was the reason, but you can ask the helpline in a 'non-specific' way...

I think it cost me 30 euros for a small alteration in the paperwork...grrr...before we went to the airport.
IF you don't remedy it, and they catch it at check-in, they can refuse boarding. It IS petty, and a ridiculous amount of money to be charged for a simple amendment to the boarding pass- but they hold all the cards,(no pun intended!) unfortunately.
It is too long ago to remedy it for free, I guess...and it IS ridiculous, as I said. However, it all depends upon who checks the boarding pass, and whether they choose to be an a..hole...and more often than not they DO. THAT is why they get the job
If I can find out anything today, I will post it here.
Edit to add:
A quick GOOGLE under the problem heading revealed this:
http://www.pprune.org/passengers-slf-self-loading-freight/410631-spelling-mistake-fr-booking.html

Ignore the typical troll comments at the bottom of the thread
The other comment about altering the boarding pass with photoshop or MS Paint is also worth considering
Another quick Google :
http://www.lonelyplanet.com/thorntree/thread.jspa?threadID=1774204

Hi This happened to me all I did was when I got to the airport I went to the ryan air desk and pointed out the mistake to the person on the desk. they looked at my passport ans signed my boarding pass and all was ok. had to do the same on return flight.

As long as my passport was the same as on the boarding pass it was no problem.

1. Call and ask ..871 2460011
2. Don't say a word if they see it say you introduce it right and fight till the death....

Just call....

Happy outcome? I hope so