Van’s and Alternative Engines
Van’s recently posted a Service Bulletin regarding the modification of RV-10 engine mounts. The problem with the engine mounts is that they will not accommodate certain variants of the venerable (I)O-540, A crossbar that runs near the induction sump interferes with certain models of cold air sumps such as those offered by Barrett Performance.
In the SB Van’s says that “it is the builders responsibility to assure that any NON-Lycoming engine (including ‘clones’) be dimensionally equal to that of the stock 260hp Lycoming (I)O-540.”
Van’s has always held firm on the insistence that 260hp be the limit for this aircraft and there have been some who have increased the performance of the (I)O-540 D4A5 engine through the addition if different ignition systems, higher compression pistons etc. I am unsure as to what the driving factor is for this close adherence to a horsepower rating. Is it weight and balance, VNE, risk of litigation?
It seems to me that the builder should have the unrestricted choice as to which power plant he/she puts in the aircraft. The rules under which we build these EXPERIMENTAL aircraft allow us to put any type of power plant in the aircraft as long as the installation meets acceptable building practices and standards.
It is the pilot who is controlling the higher horsepower engine via the throttle that keeps the aircraft under the VNE speed. It is the builder who compromises when it comes to weight and balance. The heavier engine up front will extort a price when it comes to the weight needed in the rear to balance the aircraft.
As for the litigation, I think that there have been too many instances where the spouse of a pilot/builder has brought a law suit as a result of an experimental aircraft crashing. Wasn’t that spouse in full awareness of the construction of the aircraft and the implicit risks involved? Maybe its me and I just don’t get it.
Van’s is doing it correctly when it comes to producing a kit aircraft. They should offer only one engine mount. The one for which they have done the testing prior to bringing the aircraft to market. Let the market produce the modified engine mount that supports other engines. Then let the builder do the verification testing in a 40 hour test schedule. That is what it is there for.
I am all for making modifications to aircraft. That is what this blog is dedicated to. We need to design test and bring innovative products and processes to help with the evolution of kit aircraft. We will modify them to meet a specific mission. The reality is that the mission is subtly different for every builder out there.
Dave