Twin Commander 500 Series

Although not the fastest twin ever made, its one of the best engineered. Cabin size and comfort are strong suits.

By dint of good engineering, good construction methods or just good luck, some airframes clearly stand far above others when it comes to reliability and robustness.

Only a handful of airplanes meet this description but among them is certainly the big Commander twins, including the 500 series. When first introduced, Rockwell International touted this design as being among the stoutest most reliable airframes ever conceived by man.

The reality turns out to be not too far from the truth. Indeed, Commanders do have a reputation of mechanical excellence, although theyre not without their quirks.

And everyone knows the airframes are tough as nails, as evidenced by Bob Hoovers impressive wring outs of his Shrike during the annual airshow season. Somehow, we cant imagine Hoover pulling off his routine in anything other than a Commander.

In our last Used Aircraft Guide on this model, readers wrote to rave about it reliability and freedom from breakdowns. And some of these guys have owned everything from Navajos to P-Baron, so they have some basis of comparison.

On the other hand, twin buyers also well remember the ugly incidence of expensive spar corrosion that surfaced nearly a decade ago and potential buyers rightly worry about a model that has been orphaned by the original builder.

These arent showstoppers, of course. The Twin Commander-and its turbine variants-are desirable airplanes for certain missions and there are enough of them in the field to make it worthwhile for one company to consider a re-engine project, using the new eight-cylinder V-8 developed by Orenda. If the Aero Commander looks vaguely like an Aerostar, theres a reason. Like the Aerostar, the Commander is a Ted Smith creation. The first model 520 appeared way back in 1952, even before the Apache and the Cessna 310 introduced the idea of light twin ownership to the masses.

After the 520, various 560 models emerged but the straight 500 line and its variants are the most numerous and affordable for anyone in the light twin market.

Aimed at competing with other light twins like the C-310 and Piper Aztec, the first 500s were equipped with relatively puny (for an Aero Commander) 250-HP engines. They sold for $80,000 which, in 1958, was a pile of money and made the Aero Commander pricier than the Cessna 310 by a good margin.

This 500 had carbureted Lycomings that were a welcome relief from the pricey geared 295-HP GO-480s used on the Commander 560. But the airframe and wing were identical, which is to say massive and built like the Brooklyn Bridge, at least with regard to structural integrity if not corrosion resistance. The wingspan is nearly 50 feet long and the airplane weighs in at 6000 pounds or heavier, making it a not-so-light twin after all.

In 1960, Aero Commander switched the 500A from Lycoming to 260-HP fuel-injected Continental engines claimed to put out an extra 10 horsepower each with fewer cubic inches. Sadly, it didnt work out that way. Aero Commander pilots say the 500A is not nearly as sprightly in the air as the 500, despite book figures that claim it performs better.

More Gross Weight
In those days, with a lively market and lots of wheeling and dealing in the OEM world, the manufacturers often jumped from one engine supplier to another at the drop of a hat and Rockwell did just that with the 500B. It had 290-HP Lycomings with three-bladed props, the combination of which raised the gross weight by another 750 pounds to 6750.

500A production was short-lived-it went out of production in 1963-but the 500B continued to 1965, when the 500U appeared. Presumably, the U stood for the utility category rating bestowed on the aircraft with this minor model change.

In 1968, the 500S Shrike-Hoovers preferred mount-came along and remained in production for more than a decade, with the line coming to an end for good in 1979. That means the newest 500S models are still 20 years old so its becoming increasingly difficult to find low-time, pristine airframes.

Rockwell connected with Bob Hoover in the early 1970s and Hoovers incredibly popular airshow act did boost Shrike sales, which topped out at about 50 by 1973. But the twin market was always spikey and the sales went into the tank by the late 1970s. Shortly after that, Rockwell was out of the light GA market entirely.

No Speed Demon
As light twins go, the Commanders arent the fastest by any stretch. Owners seem humble about speed for the various 500 models, claiming 150 to 155 knots true out of the small-engine 500s and anywhere from 160 to 180 knots from the 290 HP models, the latter at prodigious fuel flows Lycomings are noted for.

By comparison, any big-engined Cessna 310, Baron or Aerostar will toll along 20 knots faster without trying hard so speed is clearly not one of the Commanders redeeming qualities.

Neither is range. With 156 gallons usable and burning 30 to 34 GPH, the 290 HP models will range out to 800 nautical miles in still air, without reserves. No need to worry about bladder capacity here. With a full load of fuel, dont count on carrying more than two to three passengers, depending on the equipment load.

Handling, Control
Watching Bob Hoover work his magic, you might assume the Commander to be featherlight on the controls and as well balanced as a Bonanza. Well, not quite. Big, solid and stable are the operate words, according to owners who know and love their 500s.

Anyone whos seen Bob Hoover do touchdowns alternately on the left and right wheels in the Shrike might expect that control authority can be added to the list. Just for fun, we asked Hoover if he could do the same airshow maneuvers in other twins such as a Baron or C-310, or whether the Shrike had some exclusive qualities.

Although Hoover stopped short of saying he couldnt do the same maneuvers in the other aircraft, he noted that the Shrike was stressed for more Gs (it can pull 4.4 Gs positive thanks to its utility category rating). But were told that he actually finesses the Shrike through his sensational routine with low G loading, within a 2G profile.

Pondering the matter a moment, Hoover volunteered one elusive Shrike quality none of the other aircraft possessed: It shows up-get this-at zero airspeed with full power in the vertical. Where most other aircraft have a tendency to torque in this position, said Hoover, the Shrike holds true because of the tail dihedral, and its ability to hold aileron effectiveness down to no speed at all.

Obviously none of this matters much for Joe Bag-a-Donuts tooling along the airway from Des Moines to Dubuque. Or does it? The aircraft has surprisingly low stall speeds for a heavy a machine-59 knots dirty for the Shrike-and has good low-speed handling-a Vmc of 65 knots. This translates to some extra margin in slow speed operations and the all critical engine-out scenario. In fact, pilots consider the 500s to be good short field airplanes.

But watch out for this quirk on the initial taxi and takeoff roll: Due to the hydraulic nosewheel steering, pilots must learn to taxi and start the takeoff roll with judicious taps on the brakes to steer. Thats because the first portion of travel on the pedals works the nosewheel steering, and the remainder triggers the brakes.

Loading
One thing that gives Commanders their big airplane feel is that theres a separate door for the pilots in front and one for the passengers in back and another for the baggage a bit farther rearward.

No crawling around the seats as in a Cessna 310 or Aztec. Depending on fuel loading, the airplane can accommodate seven people-five in the passenger cabin.

The high-wing design-with engines right there out the window-has one notable drawback. Inside the cabin, theres a high, resonant noise level thats worst in the center seats alongside the prop tips. Tweaking the RPM back helps but that doesnt do much for speed, which the Commanders arent overburdened with.

If you travel with most of your household belongs, good news: The Commander has cavernous baggage compartment that will swallow large items-golf clubs, scuba gear-weighting up 350 pounds. A generous CG envelope makes the aircraft almost impossible to load out of the envelope, according to owners. For this reason, Commanders are popular with some charter operators.

Safety
Our check of accidents over the 10-year period between 1989 and 1999 revealed 27 accidents involving 500 series aircraft, 13 of them were fatal to some or all occupants. Theres no apparent pattern to the fatal accidents. At least two involved engine-out events in which the pilot evidently mishandled what should have been a survivable engine failure; one involved weather and another apparent pilot disorientation.

In one bizarre fatal accident, two Commander 500 pilots working for a Kansas part 135 company crashed and burned after apparently engaging in dog fighting to pass the time on a deadhead leg.

Among nonfatal accidents, by far the most grief involves landing gear problems, including gear collapses, inadvertent gear-up landings and inadvertent retraction while on the rollout. Although Commander have a gear handle latch to prevent inadvertent retraction, no squat switch is provided to give an extra measure of security.

Foolproof Fuel
We noted only one instance of fuel exhaustion stemming (apparently) from pilot rather than mechanical factors. The Commanders fuel system is quite simple even though there are normally five fuel tanks-two in each wing, one in the overhead fuselage. Fuel feed is completely automatic so the pilot cant really foul it up, as in other light twins.

No crossfeed, either and just a single fuel gauge that gives a reading of the total fuel in all five tanks together. It has one idiosyncrasy, however. The gauge peaks at 135 gallons and the needle wont budge for almost an hour until the first 21 gallons-of the 156-gallon usable capacity-have been burned off.

Theres only one fuel filler access for all five tanks, located on top of the inboard right wing. It pays to check the cap before flight. In one accident, the fuel cap chain was caught between the neck of the tank and the cap, and fuel siphoned from the tank, running it dry.

According to one operator, however, the biggest fueling safety hazard is posed by line personnel pumping in turbine fuel instead of avgas. Its easy to see why.

The piston and turboprop Commanders look alike and, in some cases, operate side by side. Pilots and owners are well advised to hawk the fuel truck. You have to check that cap anyway, so you might as well standby during fueling.

CG Stability Quirks
An earlier study of accident trends among Commander 500-series aircraft by The Aviation Consumer, at the end of the last decade, showed three in-flight airframe failures during a five-year period.

An FAA study of structural failure accidents between 1966 and 1975 showed that the Commander twins had the second worst record among 11 classes of twins, second only to the Piper Twin Comanche. And the accident numbers werent exactly low, either.

The FAA discovered that the stability of the original Commanders had a fatal weak link, a dangerous instability when loaded near the aft CG limit. No fewer than 22 cases of in-flight structural failures were blamed on extreme pitch sensitivity at aft CG.

However, the problem was corrected in 1975 by Airworthiness Directive 75-12-9, which required installation of bob weights in the control system of all 500, A, B, U, S and other models. Buyers should double-check that this AD has been complied with. Since the AD, there have been few if any structural breakups.

Some models have only one hydraulic pump, on the left engine. Lose that on departure and you wont be able to retract gear. Since only hydraulic pressure locks the gear in the up position, lose the engine and the pump and the gear will flop down when you can least afford the drag. Thats something to think about when departing a short runway with obstacles where engine-out performance is marginal, at best.

Maintenance
The great hue and cry over Commander spar corrosion has largely subsided, given the ADs and the fact that uneconomic airframes have been scrapped. That said, owners are both sides of a very narrow fence with regard to maintenance costs.

Owners tell us the aircraft is sturdily engineered to avoid the nasty design glitches that plague other twins but that doesnt mean this is a maintenance-free airplane. Far from it. Commanders are not for owners who want to own a twin on the cheap.

Parts can be expensive and hard to come by and owners universally report that progressive maintenance of some kind is the best way to keep this airplane in shape.

One shop told us an average annual inspection for a Shrike would run $3000 to $4000, barring unusual problems. But one owner complained about spending $8000 annually for maintenance. Some years it can go as high as $10,000 if you need to work on engine mounts or redo all the metal behind the exhaust, wrote one Shrike owner. Parts can be found, he continued, but they will cost you some pretty big bucks. Two wheel rims run more than $4000. Ted Smith built this plane to military standards, thus it is built like a tank.

Said another Shrike owner, who adores the airplane, This is a 20-year-old hydraulic airplane with all the seals and pumps that go with it. Youve got to be conscious of parts. Im constantly on the search for them. Ive had some on order for two to three months. Most owners and repair shops, however, say theyve had no problem getting parts, even though it may take some searching.

A search of Service Difficulty Reports provided by the FAA disclosed no particularly distressful area, with the exception of a rash of Bendix magneto problems (and subsequent mag overhaul problems). Though the aircraft is one giant hydraulic system (gear, brakes, nosewheel steering, flaps), we uncovered only half a dozen reports in the SDRs of problems with lines, pumps or seals during the five year run.

Despite their low 1400-hour TBO, the 290 HP Lycomings seem to stand up well. We found only occasional engine grief reported in the SDRs: an engine bearing failure, a failed crankshaft, broken rocker arm boss, couple of cylinders with holes.

Bob Hoover told us he figured with all the rough treatment he dealt his Shrike engines-shutting them down when red hot-he anticipated they wouldnt last 1000 hours. But his overhaul shop in California (Victor Aviation) told him they could have flown another 500 hours after the prescribed 1400-hour TBO.

Nevertheless, operators should keep up a healthy war chest for engine reserves since these motors will command about $16,000 to $18,000 a pop to overhaul. The Hartzell props seem to stand up well on the Commanders, too. Hoover volunteered that he marvels at how flawlessly they work, despite continuous feathering and unfeathering during his aerobatic routine.

Despite all the gear collapses noted in the accident roster, there were surprisingly few SDRs on gear problems. But we did catch several reports of cracked brackets, ribs and assorted flap-attach hardware blamed on presumably too-high flap-lowering speeds by pilots, suggesting that pilots overlook the max flap-lowering speeds (half flaps, 130 knots, full flaps only 118 knots) because of the high allowable Vlo limit of 156 knots.

ADs
The horror story for Commander owners goes back to the mid-1990s when the airplane was saddled with a raft of ADs after corrosion was reported in the spar caps. The fixes are expensive and we recommend a thorough check of the records and the aircraft itself for compliance with them.

The worst-case scenario bad beyond description and involves disassembly of the wing and replacement of the lower spar caps, a fix that could conceivably cost more than the value of an older airplane. More than a few have been scrapped by owners caught in the corrosion crunch.

A mod shop that markets a spar upgrade for Twin Commanders. Check out the Sauders Super Spar from Aviadesign. Also look into Air Center, long one of the most active Twin Commander shops.

Best Models?
The corrosion AD hasnt affected the resale value of the airplane much, if at all. Assuming the potential for problems isnt a factor, which of the 500 series is the best selection for a used-aircraft buy? For relative economy, the straight 500 with 250 HP powerplants gets the vote of users for short people hauls where a 150-knot block speed is acceptable.

The 260 HP Continental-powered 500A universally appears to draw a thumbs-down rating. Those Continental engines are like having AIDS, sneered one operator.

But aficionados of the big-engine 500s say the straight 500 is a completely different class of airplane. That leaves the choice between the 500B and the Shrike. Many seem to prefer the B models because they have more useful load-2200 to 2300 pounds.

Compared to What?
The Commander 500s arent really bargains on the used market. Buyers may be surprised to see that a Shrike, on average, is going for a few thousand more than even the perennial favorite 58 Baron, possibly because the Commander is cabin class and the Baron isnt.

Although Commander owners like the commodious seven-seat cabins, we suspect the average pilot will fill the rear only occasionally. If lots of passenger seats were the main objective, a Cessna 414, 421 or a Navajo would fill the bill more satisfactorily, deliver more speed and perhaps cost less to maintain on a seat-mile basis.

Opting for the Commander, then, would seem largely to satisfy a wish for an unusual aircraft and a willingness to trade speed for a fatter cabin and a bit more payload.

Owner Comments
My contact with an Aero Commander twin began in May 1996 when I contracted with Gary Gadberry of Air Center, Inc. (contact 423-893-5444 or www.aircraft.com/aircenter )to purchase one of his Shrike Conversions. Ten months later I took delivery of a drop dead gorgeous airplane.

The work done to it was very extensive. Air Center installed an extended nose with an integral radome, eye brow windows above the pilots and co-pilots heads, flap gap seals, an extended tail cone, a square tail cap with teardrop beacon, all new windows, new interior, a new one piece metal instrument panel and a strip and paint.

I elected to have some other work done while this was going on. The paint shop-Grays Aircraft Refinishing-replaced all of the control bearings and all of the steel screws and Camlocks with stainless ones. I had the propellers and governors overhauled. All of the radios were replaced and we added GPS, slaved HSI, moving map and WX-10.

Replaced the Prestolite starters with Sky Tec starters. I highly recommend this mod- saves 20 pounds and the light weight starters really spin the engines. Also added wing tip strobes.

This is the first airplane I have ever owned and the only light twin that I have flown. The only other twin which I have flown is the Grumman S-2 Tracker. I wanted a safe, well-built (rugged, as in made by the Grumman Iron Works), stable and roomy airplane which would have the capability to haul wife, kids and grand kids. Something like the S-2, but we could leave off the tail hook.

Well, this one isnt made by Grumman, but Rockwell aint bad. This is one stout airplane! Its built like a tank. Its a very stable aircraft, but not in the least bit boring. Its powerful, responsive and fairly fast. A big airplane.

The large tail and long fuselage make engine out flying almost a non-event. It cruises at 176 knots on 30 GPH at 65 percent power. The useful load is 2200 pounds. This translates to 1300 pounds available with full fuel. The baggage compartment is cavernous and has a capacity of 350 pounds. We recently made a weekend trip with six people, baggage and full fuel and still had 285 pounds available.

The systems are dirt simple. There are five fuel cells, filled by one filler and interconnected so that they all drain to a common sump which feeds both engines. Fuel management is a snap.

The landing gear is hydraulic. Mine has two engine-driven pumps, one electrically driven pump and a nitrogen bottle all plumbed together. The emergency gear extension procedures: Place gear handle in the down position. Thats it.

The nose wheel steering takes some getting used to, but after a few hours it becomes second nature. This has not been a cheap airplane to own. One must bear in mind that it is a fairly complex machine which is almost 40 years old. During the two years which I have owned the airplane, I have replaced the following: all four magnetos and wiring harnesses, both vacuum pumps, left and right fuel boost pumps, left engine driven fuel pump, No.2 navcomm and CDI and the manifold pressure gauge.

I have overhauled both Bendix fuel injector servos and distributor assemblies and replaced the seals in all three landing gear and both engine-driven hydraulic pumps and the right engine-driven fuel pump. I flew the aircraft 101 hours in 1998 at a cost of $26,560. This includes fuel, insurance, hangar, oil, 50 hours inspections, annual inspection, unscheduled maintenance and charts, publications and dues.

The cabin is roomy and comfortable. The cabin entrance door is located under the wing with the sill at a height of only eighteen inches. My in-laws have had hip replacement and back surgery, yet can easily enter and exit the airplane. There is no way they could enter a Baron, C-310 or Aztec.

Both the baggage compartment door and cabin door are located under the wing, which is greatly appreciated when it is raining. I elected to forgo the front door. In my opinion it adds extra weight, extra drag, about eight feet of potential leak and detracts from the appearance of the airplane.

In my opinion, this airplane is one of the yet-to-be-discovered jewels in aviation. The 500B models have about the best weight carrying ability of any light twin, have distinctive good looks, are still reasonably priced and do not have the spar cap problem of the 500S. Theyre a delight to fly, easy to land and are a very stable instrument platform.

-Name withheld by request


In response to your request for feedback on the Aero Commander, Merlyn Products, Inc. (MPi) has developed some products for the Commander 500B, S, U and 560F. Some of these STCs can be extended to other models. The Lycoming TIO-540-J2B(D) engine is STCd at 350 HP for the above models. This also allows for a gross weight increase of 2050 pounds on the 500S and U models to 8800 pounds. The increase in empty weight is 250 pounds. The gross weight for the 500B and 560F is 8000 pounds. So far, it appears that the aircraft are being operated around 7800 pounds.

MPi also makes a fuel increase kit of 100 gallons. Its actually slightly more, but the original 156 usable gallons is more like 149 gallons, so MPi chose 244 usable gallons to be on the conservative side.

MPi also has an STC to install IO-540-MIA5 or -MIC5 engines in place of the EIB5 narrow deck engines. The MIA5 / MIC5 wide deck engines can have a 2000 hour TBO and are a current production engine.

This STC is currently being amended to increase the horsepower to 300 from 290 HP and to increase the gross weight about 175 to 250 pounds.

With regard to the aircraft, it has always been a mystery to me how Ted Smith championed such a superb handling aircraft that does everything right. It virtually cannot be loaded out of CG limits and is reasonable to maintain. Then he built the Aerostar. Regardless, the Shrike was a great basic aircraft to do a substantial STC project on, and never once presented any challenges with regard to meeting the FAA rules.

If I ever make any money in the aircraft business, I will own one.

-Hugh G. Evans
Program Manager
Merlyn Products, Inc.
Spokane, Washington
509-838-7500

The 500 Commander is the finest non-pressurized twin ever built. Ted Smith built this plane to military standards; thus, it is built like a tank. With a stall speed of 58 knots dirty and a Vmc of 65 knots, the plane can really get in pretty short.

When not at gross and a 100-degree day, I will take it into a 2500-foot field without a second thought. The Commander has very long wings-49.5-feet-which means great flying qualities, but dont taxi in close quarters.

-John R. William
Los Angeles, Calif.


My relationship with Twin Commander has been love-hate. I realize youre covering the piston models only but here are some notes on the turboprop version. I own a 1967 680V, the first Commander to have turbine engines. They are 575 HP Garretts.

The love part goes like this. Let me qualify myself by saying I have 2400 hours total time, 500 hours in an Islander and 450 in a Navajo. I am a general contractor and sideline in building homes near a 3000-foot mountaintop airstrip at 2900 feet MSL. This has given me a fascination for airplanes that can carry a lot and land short.

The airplane is a joy to fly. It takes off and lands relatively short (1500 feet, medium load, standard day.) It flies fast; 250 MPH and mine is the slowest one built.

The 1000 HP models approach 400 MPH. It flies slow: stall 85 MPH with good control and plenty of warning buffet. Stalls are gentle and no wing drop. Recovery is simple; add some power and put the nose down a little.

Its a very stable instrument platform, likes steep turns and is very agile. You can really crank it around in a hurry if you want to. Twin-engine and single-engine climb is excellent. The later models climb faster on one engine than most gas engine twins can on two.

Flying on one engine is easy. Once you trim it up, you hardly notice it. Its rumored that one large flight department routinely shuts down an engine en route to extend the range. Descents can be made quickly also by pulling the props back to flight idle. Youll be coming forward against your seat belt. Drop the gear and flaps and you can descend at 4000 FPM. (Save this for emergencies only.)

The weight carrying ability is excellent; 3800 pounds useful and the envelope is easy to work with in all situations. The airplane has sleek, aerodynamic lines and looks good on the ramp and in flight. The only tricky part is steering. But once you learn, its okay.

The hate part goes like this. I sold my Navajo to purchase the 680V. This airplane had been heavily modified with a Shrike door and high-density seating for 11 people. The aft baggage door was enlarged to 3 feet square and a hole was cut in the aft passenger bulkhead to allow carriage of long objects.

All this neat stuff overloaded the logical side of my brain and emotion took over the purchasing process. I allowed the seller to do a pro-purchase inspection for me at the shop that did all his maintenance for a freight outfit.

Naturally, the report came back good. If you get one thing out of this article, let it be this: Always get an annual inspection as part of the purchase of an airplane. This requires an I/A to sign the log and put his license on the line.

As soon as I got the airplane, the problems started surfacing. This is a long story but the bottom line is, I bought a restoration project. I have put more in repairs then I paid for the airplane.

The good news is a company named Twin Commander Aircraft Corporation (contact 360-435-9797 or www.twincommander.com.) has adopted the orphaned Commander fleet.

Under the leadership of Jim Matheson, they have built up a network of authorized service centers so I have been able to get all the parts I have needed through their network.

There are not many options for Commander owners to train. The Bethany, Oklahoma Flight Safety International has the only Commander flight simulators in the world. But they are a top-notch outfit.

Regarding the cost of operation, I am sure if I had paid more initially and gotten an airplane in better condition, my maintenance costs would be a lot lower. Fuel burn is about 70 gallons an hour at cruise.

In summary, Commanders are great to fly, a true pilots airplane. Its a workhorse that handles like a Ferrari.

Like all turboprop airplanes, theyre not for the weak of wallet.

-Howard Payne
Monrovia, MD


Also With This Article
Click here to view the Commander Comparisons.


Editors note: The Twin Commander Aircraft Corp. can also provide information on the Renaissance Commander program, which refurbishes turbine-powered Twin Commanders.