I used them in my TF P-40 Nergall, and am currently using them in a similar size Hellcat. I've had zero problems with them but I will admit that I only fly off of paved surfaces. If you fly off of grass, dirt, or other unimproved type surfaces it might be a different story. The Robarts do have to be installed carefully so as not to twist them when they are bolted to the mounting rails as that will cause binding. I would also caution against using them in an airplane much over 10 pounds (even though my Hellcat is 11.75!) which is all that they are rated for. If you get sideways with a heavier airplane you will most likely bend the locking arms. While I have had good luck thus far with the Robarts I do have to tell you that Sierra Precision make a 100 degree rotating retract which is light years better. They are more expensive but worth every penny. Keep in mind when comparing the Robart and Sierra retracts that the latter come with the functional oleo struts while the former do not. By the time you purchase a pair of struts to go with the Robarts the price difference is not really as much as it would initially appear. I have had great success with air retracts and am not yet sold on the electrics as they seem to be having lots of teething problems. If I were building a TF P-40 at this moment there is no contest in my opinion, I would be installing the Sierra gear. (And, in fact, I am putting them in my second Hellcat which is under construction.)