Search the Community

I have heard some discussion regarding the advantages or disadvantages of the retractable step. While most will agree it is cool, some disagree as to the advantages. In a recent Facebook post I saw that someone had their vacuum system removed and has the step hanging out without detrimental effect. Before the electric step conversion, I had left my step hanging (original crank equipped aircraft) by accident and recalled noticing because my speeds were lower and the ball was slightly out. Anyway, decided to do some testing on a short trip yesterday and verified that it does make a difference. In fact, it was quite notable when paying attention to the numbers. I’ll call it an average of about 3 knots. I repeated putting the step up and down a few times and it was consistent. I made a rather crude video for those who must see: https://youtu.be/zOD2mXwcOIk. There are two reasons for the significant speed change. One is obvious, it is that the retractable step has zero aerodynamic abilities. It is a large square tube with an equally blunt step. The second is less obvious, but it is the effect of asymmetric drag on the airframe. Those who have left the step out may note that the ball on your turn coordinator will be ever so slightly out of center, requiring a touch of left rudder to counter it. Just like slipping a plane on final induces drag and gets us slower and lower, this slight slip slows our aircraft down. What percent of the drag is due to the step drag vs slip I’m not sure, but it clearly adds up. Mooney’s are especially sensitive to good rigging, as noted by some wide variation in reported performance. Modern Mooney’s have a more aerodynamic step, so Mooney opted out of the retractable step business in the late 60s. I think it would still be cool to have it retract, but it might be somewhat invasive. Anyway, would love to hear from others with detailed side by side speed comparisons of step up or down or on or off. While I am on the taller side, I still appreciate the step and I know my pax do as well.

Thought I would start a new thread on an old subject, the Retractable Step on our vintage Mooney’s. We all know that they are worth a couple of knots when retracted and make boarding a little easier. However, there are reports that they have been getting more difficult to maintain, between difficulty getting the pneumatic bellows or cables binding or breaking for the crank style. Because of some peer pressure, I tackled an electric conversion. My goals were to make it weigh no more than the original installation, be easy to install and maintain and to be reasonably priced. As mentioned in another thread, I feel like I am close to meeting these goals. My 1964 E model had the original crank style. The actuator I used has 200mm travel and about 18 lbs of force. To get the required travel of just over 15”, requires use of a pulley mechanism, similar to the way the pneumatic step works. In the end, the actuator is modified with a relay circuit for automatic reversal and some hardware to mount the pulley and to mount the actuator to the aft bulkhead. The actuator has built in limit switches. I still have a little work to do on the up-limit, as there is a little dithering which eventually self clears. The load near the top of retraction is quite significant due to the pulley loads and the down-assist spring load. I am considering a stronger actuator, but it is much slower. I suppose the only time the speed would be important is in an emergency, and in those cases, the step is a minor convenience only. I reuse most of the existing hardware, with the exception of the actuator, one fabricated cable and the addition of a single down-assist spring. Repeat installations (not including build up of the actuator) would be about three hours if you have electrical power available aft (I have aft mounted battery) I installed this as a minor alteration. I made the assessment based on my previous work with my ACO on Auto-Lean and Auto-Heat. Mileage may vary with your own IA or FSDO. If there is enough interest, I would be willing to pursue a PMA kit with my ACO, eliminating any legality questions. Would want to do a local pneumatic step aircraft as well. For DIY folks, I am also happy to talk you through your own buildup, just contact me via Email. Video can be seen here: https://youtu.be/5vfc8iPqxwM Actuator with step down Actuator with step up, cable is new, trunbuckle is re-used.

Hello All - My partner and I purchased our 1968 M20F back in June of this year and the prior owner indicated that the retractable step servo boot had been patched but was in rough shape. He also conveyed that he had been placed on Brittain's backorder list (more than a year ago) for the servo boots for when they started making them again, but he and others indicated it could be quite a while. We recently received communication from Brittain that they were producing and shipping the new parts now and asking if we were still interested. I was wondering if anyone has already recieved their new servo boot and had any reviews on them. Apparently Brittain is insisting you ship the old servo unit to them and they will ship the unit back to you with new components (boot and perhaps others?). Thanks!

Hello All - I'm wondering if anyone can help me with the proper lubricant for the retractable step on vintage Mooney's. I've witnessed from my own experimenting that too thick of a lubricant will cause binding. I've seen one post that referred to Teflon spray and a lubricant recommended in the service manual, but I can't find a portion of the service manual that refers to lubricating the step. Thanks!