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Wednesday, October 1, 2003

Rebirth of an Old Jet

Bob Howie, Contributing Editor

Garrett Aviation's FJ44 Eagle conversion to the Cessna 500 & 501 fleet adds awesome performance, thanks to new engines and extensive structural modifications.

Like an aging beauty who goes to her favorite surgeon in hopes of fighting time, the matriarch of Cessna's highly-successful and hugely popular Citation light jet line is being reborn in Houston.

Garrett Aviation at Houston's George W. Bush Intercontinental Airport is offering owners of Citation 500 and 501 series airframes–of which more than 300 were built–the opportunity to convert to the Garrett FJ44 Eagle II modification.

With performance gains that allow the Citation 500/501SP family to compete with the newer generation of owner-flown light jets in terms of range and speed, the Garrett FJ44 Eagle II modification is more than just fancy paint, new engines, and a new interior.

Off come the venerable Pratt & Whitney JT15Ds to be replaced with new Williams FJ44s. But, this is a program that is more than just gilding an aging lily.

Garrett Aviation recently bought the program from another Texas firm that originated the modifications as part of Garrett's continuing offerings of aircraft modifications and retrofit programs.

Garrett officials said the FJ44 Eagle II program fit neatly within the company's ongoing interest in providing aftermarket performance enhancements in much the same way the company has participated in Jetstar, Jetstar II, and Aero Commander mods.

"The FJ44 Eagle II program was a natural progression for us as a company and it's just another program that we can offer customers," said Lane Clapsaddle, Garrett's customer services representative and contact man for the program.

"It gave us another program, an opportunity to work with another manufacturer and engine maker and now that we are just starting this program, we are getting a mix of interest," he said.

Much has been written of the performance gains associated with the Garrett FJ44 Eagle II program, but not so much about what goes into turning a customer's Citation into the Eagle.

Clapsaddle pointed out that the process is rather extensive, beginning with a complete initial check of all airframe and systems components and ending 12 weeks later when the Eagle-modified Citation rolls out of the hangar.

"Each candidate for the modification is thoroughly inspected; what amounts to a very thorough pre-buy inspection so that not only we know the condition of the airframe, engines, and systems, but so does the customer," Clapsaddle said.

"Everything is looked at including all [exterior and interior cosmetics] so that all concerned know the condition of the aircraft before it enters the shop. That way we know whether a condition existed prior to the project start or whether some [ding] was caused during the process," Clapsaddle said.

He said the initial inspection process, which includes a comprehensive flight check, clearly identifies any issues that must be dealt with prior to final sign-off by Garrett and work an owner might consider having done while the airplane is torn apart.

And, torn apart the airplane quickly becomes in the shop.

Off come the wings as the fuselage is set in a cradle. Next, it's off with the engines, nacelles, and pylons. Out comes the interior–all of it including side panels–and the instrument panel is likewise removed. The floor comes up and plywood panels are laid down to protect the airframe as various technicians involved in the process begin their work.

"One of the things about this program is that it really isn't new technology from the standpoint of working on the aircraft," Clapsaddle said. "Any technician or service center with Citation experience will be quite familiar with the airplane after the modification process is completed. The wide availability of maintenance is another program plus."

Ever wonder what the infamous hell hole looks like without all the stuff? It's a pretty barren place after all equipment is removed so modifications can be made to the engine support beams, one of the more interesting aspects of the project.

"The through-beams that support the Pratts are spaced differently than what is required by the FJ44s and because of that, another beam aft of the forward beam supporting the Pratts is installed," Clapsaddle said. But, instead of removing the forward beam, it is left in place to provide additional support for the new engines.

"What we do is install the new support beam and then [sister] it up to the existing forward beam so it's all tied together and creates a stronger structure," Clapsaddle said. "The portions of the forward beam that exit the fuselage on either side are then trimmed flush with the fuselage, but the main part of the beam as it is tied into the airframe remains, giving the finished modification a lot of strength and support."

As the airplane is taken apart, care is taken to preserve all the existing components including all cowlings, pylons, plumbing attachments, inlets, and related coverings.

Sheetmetal technicians will modify the original cowling components to accommodate different placements of items on the Williams engines versus the Pratts, thus resulting in significant time and cash savings.

One key component of the modifications includes changes to the 500/501SP wings, which require a 27-inch extension to each wingtip–the long wing modification–as well as what is also called the fat wing mod; a reworking of the wing at the root in order to increase fuel capacity. "This is done to both increase range as well as giving the aircraft the ability to fly at 41,000 feet, something the straight 500s and 501SPs can't do," Clapsaddle said.

As part of the wing work, technicians also inspect all the wing-to-fuselage connections. New bushings are included in the fittings and new bolts replace those taken out. The tail is also modified and beefed up as part of the conversion process so the entire structure is more robust in order to support the modifications as well as the performance enhancements.

The Eagle wing modification, or the fat wing, which is a modification at the wing root to increase tankage as well as add some benefits in low-speed handling characteristics, also includes a new upper skin with a fiberglas fairing to fare the new upper skin into the existing wing.

The leading edge cuff is reformed to cover the wing root and a larger circuit breaker is added to the panel in order to handle the increased amperage fed to the new, larger cuff to provide sufficient heat in icing conditions.

The entire modification is part of the supplemental type certificate that governs the Garrett FJ44 Eagle program.

One major component–more accurately, one major component that becomes absent during the process–is the removal of thrust reversers if installed on airframes that come into the plant.

"There's really no need for them after the modification is done, so regardless, they come off during the process, but you will never miss them," Clapsaddle said, noting that most Citation pilots familiar with thrust reversers may notice aft first the absence of the TR triggers.

And, because of the "next generation" status of the Williams engines versus the original Pratts, pilots will also be able to take advantage of what amounts to FADEC controls.

"There's also a new center section for the instrument panel and some modifications to the circuit breaker panels, but once they are reinstalled, they are all labeled just like before with the exception of what might be [unique] to the modification," Clapsaddle said.

As the reassembly process takes place, the checklists started when the project began are consulted to ensure that all airworthy issues are resolved before the owners take delivery.

Clapsaddle said owners can have all the airworthy issues performed while their aircraft are at Garrett or Garrett will sign off the modification with exception to airworthiness issues that are not related to the program. In that case, owners can arrange to have the aircraft ferried to the maintenance facility of their choice.

During re-assembly, Garrett paints, if necessary, those components of the airplane that require it–for instance, cowlings after they are modified to accommodate the FJ44s–but the company doesn't paint the entire airplane, although that can be arranged if an owner desires.

"The entire program is breathing new life into these airframes," Clapsaddle said. "And, even at $1.7 million for the modifications, given the acquisition costs of these models, this program is making the 500/501SPs very competitive in today's market."

A Garrett FJ44 Eagle II will cost the buyer about $2.95 million, including airframe acquisition. Its younger stable mates, the CitationJets CJ1 and CJ2, by comparison, typically cost up to $4.9 million and the new Raytheon Premier I chimes in at $5.2 million in the owner-flown category of light jets.

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