50Dash4: Power Transplant

 - February 27, 2008, 5:07 AM

After a record 30-year run, Dassault quietly stopped building its once popular Falcon 50 last spring. More than 350 of the trijets were delivered before the final version, a Falcon 50EX, rolled off the assembly line. About 240 were the original Falcon 50, and the remainder were the 50EX.

A Dassault Falcon Jet spokesman said production of the first three-engine business jet ended because “there has been a market shift toward wider-cabin aircraft with stand-up room such as the Falcon 2000. Given this shift in demand and Dassault’s focus on it, upgrading the Falcon 50EX further was not a reasonable business proposition for our company.”

The Falcon 50 did not disappear willingly, though. As the spokesman explained, “In the late 1980s and again in the 1990s demand for the airplane wavered near reasonable and profitable production rates, but each time it was followed by resurgent sales, especially after introduction of the latest version, the Falcon 50EX.” One reason for the Falcon 50’s staying power is its nearly 24-foot-long cabin, only two feet shorter than that of the 2000EX, but nine feet less than the inside length of a Falcon 900. The 50’s interior is more than six feet wide, with a maximum floor-to-ceiling height of 71 inches. The last Falcon 50EX was
delivered in early January.

There are still about 240 original Falcon 50s in service around the globe, offering a sizeable cabin and three-engine security at a relatively modest price. A pre-owned Falcon 50 currently commands between $7 million and $11 million, while a recent 50EX starts at about $18 million.

A New Partnership
St. Louis-based West Star Aviation has partnered with Rye, N.H.-based Yankee Pacific Aerospace, forming a joint venture called Premier Aircraft, in hopes of keeping many of these Falcon 50s airborne with a performance advantage over competitors.

Yankee Pacific president Ken Goldsmith and Ken Shimabukuro, managing director of aircraft performance programs with Yankee Pacific, hope the improvements available through their upgrade of the original Honeywell TFE731-3/3D-1C to the TFE731-4-1C engines will be regarded as significant enough to justify a $2.3 million investment. The new engines allow the airplane to climb to a higher altitude more quickly and cruise nearly 25 knots faster, using less fuel than a Falcon 50.

Yankee Pacific has provided the program management and engineering design expertise, while West Star brought its considerable Falcon experience and modification facilities to the table. The actual upgrade work is handled at West Star’s Alton, Ill. facility.

The Falcon 50 owners AIN spoke to love their airplanes, which is one reason West Star has delivered five of the Falcon “50Dash4” conversions to date. One owner said that while the upgrade sounded interesting, he didn’t think he could justify the investment in upgrades. However, that could change as the cost of fuel rises and owners who were planning to sell their Falcon 50s might consider the West Star option instead.

“Domestically, the Falcon 50 will fly just about any kind of trip,” said Jim Swehla, vice president of sales and marketing at West Star. “Internationally, many folks are jumping into Falcon 900s. But at $23 million for a 900 and $32 million for a 900EX, not everyone can afford those airplanes.”

The cost of the upgrades runs $2.3 million if the owner provides his own airplane for the conversion and the airplane is not currently enrolled in an MSP plan. If the aircraft is part of an MSP plan, the cost of the new engines varies according to the amount of time remaining on the old powerplants. That means the price can range from $1.6 million to $2.3 million. If loaner engines are available, West Star can do the engine change work in four days, seven if the loaners are not available. The aircraft would also need to return to Alton to have the engines switched again when the upgrade work is completed at Honeywell, which normally takes 30 to 45 days. The conversion makes the Falcon 50Dash4 Stage 4 noise compliant as well.

During the conversion, owners can make other changes to the Falcon 50 to bring it closer to a newer model. An avionics upgrade to replace the original Collins hardware with a new Pro Line 21 system that includes dual upgraded FMS units adds $2 million to the price. In addition, West Star will swap out an old interior and add a fresh coat of paint to make any Falcon 50 look like new. While the aircraft is being upgraded, West Star can also complete the Dassault corrosion protection Service Bulletin 460, which extends the life of the Falcon 50 beyond the original 30-year life established by the factory. A $100,000 deposit is required to hold an upgrade slot.

Shimabukuro said that finding the performance gains needed to make the entire Falcon 50 project a solid value proposition included no small amount of work long before the FAA signed off the engine-upgrade STC. The first element was finding a good airplane to serve as a testbed. “We eventually found our airplane in Mexico. Then the real work began. Reprogramming of the digital engine controls alone took more than a year,” Shimabukuro said. “We did save a million-and-a-half dollars of investor money and an additional 100 hours of testing time by performing much of the engineering work with the engine nacelles still attached. That’s a new concept.”

Engine Swap
Swehla said the engine upgrade results in a 3.3-percent reduction in thrust-specific fuel consumption as well as a 13.7-percent increase in thrust at cruise altitude. In other words, a re-engined Falcon 50 will take the aircraft to altitude more quickly than its predecessor and burn less fuel once it gets there. This is all made possible by flat-rating the -4 engines to the same 3,700 pounds of thrust as the original -3 engines. The residual engine thrust allows the aircraft to maintain the 3,700-pound-thrust rating at takeoff on a 93 degree F day.

The new powerplants can push a Falcon 50 at mtow directly to FL370 eight minutes faster than the straight 50 can. Off the ground at mtow, the upgraded airplane can climb directly to FL390. Adding the new engines increases the aircraft’s overall range by approximately 300 nm when flying at Mach 0.80, while maximum cruise speed increases by 20 to 25 knots.

Hot-and-high performance shows a striking improvement as well. A standard Falcon 50 leaving Denver carries four people about 2,200 nm, while the 50EX can carry that same load 2,450 nm. The 50Dash4 Falcon will carry four passengers out of Denver nearly 3,000 nm. With nine passengers on board, the 50Dash4 surpasses the 50EX by almost 20 percent as well, carrying nine people 2,600 nm while the EX has a range of 2,200 nm.

The engine upgrade process includes replacing the engine fan and gearbox and adds the -5 hot section (the same as the Falcon 900’s). Honeywell modifies the exhaust system to a compound nozzle configuration and adds an N1 digital electronic engine control but retains the current N1 and N2 gauges. The ITTs are overhauled and remarked to the new higher 952 degrees C figure, 42 degrees hotter than the original engines. The 50Dash4 includes extensive exhaust changes by replacing the co-annular core pipe with a new short core nozzle and modifying the existing bypass inner skins, which results in improved thrust-specific fuel consumption efficiencies. The standard Falcon 50 engine mounts are retained for a total conversion weight gain of about 200 pounds per aircraft.

The maintenance intervals for the new engines also rise significantly. On the original -3 engines, the major periodic inspection and core zone inspection are 1,400 hours and 4,200 hours, respectively. On the upgraded -4 engines those numbers become 2,500 and 5,000 hours.

To make sense of the numbers I saw during my flight in N504YP, a Premier Aircraft demonstration airplane at St. Louis (ALN), readers need to understand the statistics on the Falcon 50 and the 50EX. The maximum takeoff weight of the former is 38,800 pounds; that figure is about 1,000 pounds higher for the EX. Both aircraft carry just over 2,300 gallons of fuel.

We flight planned N504YP for a multi-hour mission to see how well it climbed and how closely the aircraft matched Premier Aircraft’s claims once it reached altitude. Seven people were on board–three in the cockpit and four in the cabin. With 15,500 pounds of fuel on board, the 50Dash4 weighed in at 38,925 pounds as we rolled out of the chocks at ALN. The route was to take us west out of St. Louis toward Sioux Falls, S.D., northeastward toward Minneapolis and back in to Chicago Executive Airport.

Outside temperature at ALN was 19 degrees C. The books called for 4,700 feet of runway at flaps and slats 20. Departing Runway 17, the Falcon left the runway quickly with between 2,000 and 2,500 feet of the 6,500-foot surface remaining when we broke ground. Swehla said that, under these conditions, a regular Falcon 50 would have struggled to reach FL350 right off the ground and flown no faster than Mach 0.74. We were headed to FL390 today.

I was hoping for few delays on the way up, but St. Louis cleared us almost immediately to 15,000 feet. Off the ground, the target airspeed became 175 once the gear and flaps had been retracted, and initial climb rate was 1,600 fpm. The rate increased significantly to about 3,300 fpm as airspeed climbed to 250 knots out of the Class B airspace. The plan was to hold 260 knots out of 10,000 until reaching Mach 0.72.

Flying the Falcon 50 Dash 4 is no different from flying the standard Falcon 50. The performance chart I kept during the rest of the climb and cruise confirmed the numbers Premier Aircraft is publishing.

Will it be worthwhile for a customer to hand over $2.3 million or so for the new engines? That’s a call only an owner can make. Twenty-six minutes after takeoff from ALN, we leveled at FL390 and not long after that we snuck up to FL400. I watched the Mach meter climb as we accelerated…Mach 0.78, Mach 0.79. It finally settled on Mach 0.80 for a true airspeed of 459 knots. Not bad for a 30-year-old airplane sipping fuel as if it respected the price of jet-A today.