That advantage is not as great as you might think.

One, FBOs charge ramp fees for turbine airplanes if you don't take fuel, so you are almost always taking fuel. I haven't paid a ramp fee in years, and I almost always take fuel at every FBO I visit.

Two, the Merlin with full fuel has essentially no cabin payload left, so you have to be flying with pretty light loads.

Three, the performance of the Merlin at high weights is significantly affected. You are trading safety for a few dollars, and it climbs and flies slower at higher weights negating some of the advantage.

Four, jet fuel prices are generally more uniform and competitive place to place than avgas. Even at $1/gal better in one place, you are looking at saving, what, $250?

Five, high landing weights cost more in maintenance over time, tires in particular.


The engine on the Merlin is being asked to provide 900 HP instead of 715 HP on the Marquise, so it reaches its temp limited altitude MUCH sooner. Get into high and hot, the plane is losing power when the MU2 is not.

The Merlin is basically under powered. They are pushing what you can get from the small block TPE331. Hence the AWI feature.

When the FAA did a safety review of the MU2 in 2005, which ultimately ended up being the foundation for the SFAR, they studied how the MU2 compared to other aircraft in 135 ops. A few aircraft were worse than the MU2 and the Merlin was one of them.

Page 11 and 12:

https://www.faa.gov/aircraft/air_cert/d ... errata.pdf

I don't think these numbers are very reliable, however, but I don't have a better source.

Mike C.

I make a point of providing my Sherpas supplemental O2 when they take my bags up into the cabin of the Merlin.

Do you make a point of paying the FBO extra for fueling your MU2 as it requires three two hose trucks and 6 linemen plus a supervisor if you want to fill each cap simultaneously. The Merlin has as simple a fuel system and fueling procedure as you can get after single point refuelling.


I'd like to see the list of accidents that shows more hull losses and fatalities in the Merlin when compared to the MU2. I find plenty of ground control accidents but much less fatal crashes and bull losses.

Fortunately, no.

Having only two holes would be nice, but it really doesn't affect me much. Note that a good fraction of my fuelings only involve tip tanks, two holes, so not always so bad.


Yeah, but it is a "low wing" airplane which requires a ladder. :-)

Conquest II wins the "easy to fuel" contest. No ladder, two holes, no balance requirements, done.


The FAA didn't give us the raw data behind the chart.

I concur with your feeling the chart is suspicious, or at least, wildly skewed by unstated assumptions.

Mike C.

My mechanic has a high use Merlin operator as a client who had one side brakes freeze up while parking in the northern states. The pilot took off with the brake on and landed that way but managed to maintain control. What you describe as a massive undertaking and unobtanium parts my mechanic gathered and loaded up the parts in a few days and airlined out to change everything in the field. Guy was up in the air quick with relatively little downtime. Beware of using the parking brake in freezing temps as the brakes can be frozen and not release. Beware of using a mechanic that looks for parts in Australia that are meant to fit a plane built in San Antonio. <couldn't resist, your guy may be fine, I don't know him>

He's not my guy - I just used them for a compressor wash because they are close but Mather is a big operation (3 locations) that works on turbines of all sorts every day. I am certain they are aware that there is Merlin support in San Antonio. There is probably more to the story which is why I suggested to the OP that he call and gather more information. This was not a simple case of a brake freezing in cold weather. The Merlin uses power assisted brakes and there is some kind of valve system under the panel down by the pedals that controls the pressure to the brakes. This malfunctioned in some way and pressurized the brakes and locked them which caused the plane to head off into the weeds on landing. Apparently it was difficult to find someone to overhaul the brake controller and really difficult to R&R. Who knows, maybe Mather has no idea what they are doing. Or maybe they do. Either way if I were considering buying one I would want to evaluate that for myself and use the information as part of the criteria for a pre buy, evaluating the MX history, etc.

Yeah, but it is a "low wing" airplane which requires a ladder. :-)


Mike C.

Commanders one hole, but you do need a ladder. But in my experience, pulling the fuel hose out to accommodate multiple filling holes takes much longer than bringing a ladder out.

Not directly related to the thread, but here is a time-lapse I took of the beast getting topped off at KIXD a few weeks ago. The line guys earn their keep topping off Mu2s. Watch as the one guy fills the tip before the other and you can see the plane tip a bit.

While it takes a few extra minutes at times, one positive is that I leave every FBO feeling like I got my moneys worth....

http://flyinglog.tumblr.com/post/156816 ... ay-the-mu2

To anyone who is interested about this issue.

The only power that the brake system gets is from pilot pressure on the pedals, no power assist after that.

There are parking brake valves and shuttle valves. Shuttle valves allow pressure to come from either left or right seated pilot into the brake line. The parking brake valve puts a lock on the brake system when you depress the brakes and pull the parking brake lever. The parking brake valve is not the best design and apparantly there is an old AD by which it gets changed out at some time with a new style. The new style is a bit better. The problem with the parking brake valves is that they do not always release, this problem is more likely to occur in cold weather.

The valves are readily available and indeed a chore to remove/replace. Estimate two days one guy, they are on the forward pressure bulkhead and radios and racks have to come out to get at them.

This is the info I got from my mechanic. Personally, never had a brake problem of any kind. His free advice, use wheel chocks and leave the parking brake alone.

I just saw an ad for a Merlin IIIC claiming power brakes with anti skid. Maybe an option or STC mod?

http://www.wolfeaviation.com/aircraft_f ... A227TT.pdf

One per wing, total of two?

Or do you really mean just one hole, single point?

Mike C.

One per wing, total of two?

Or do you really mean just one hole, single point?

Mike C.

Most have had the anti skid disconnected. The brakes are not all to powerfull anyway and one relies much more on reverse thrust or ground idle to slow down. Brakes are for not running over the marshall.

Found the "power brake anti skid" system description in the mx manual. Indeed there was a "power brake" system option in these aircraft. As I said, most I have come across are disconnected, including mine.

In real world operations, do most FBOs know how to fuel an MU2, or do you need to be there to supervise?

Robert

It's definitely a problem area. Some places are fine. Others... not so much. You can usually tell via a very quick quiz of the line guys whether they really have done it before or not.

I do find ground handling on the MU2 has two weaknesses:
- Fueling, which requires ladders and multiple tank balancing
- Towing, which requires a wide towbar (dual nose wheel), doesn't work with a typical Lektro, and knowledge that the torque link needs to be disconnected

Neither is insurmountable, but both have their inconveniences.

But... for the inconvenience you get a fast, comfortable, and relatively inexpensive ride!