Uvalde, Texas, seems like a strange place for a world-class business jet re-engining company to call home. Located 70 miles west of San Antonio in a part of Texas better known for deer hunting and off-road racing than for high technology, Sierra Industries is way off the beaten path, unless you fly a bizjet, that is.
It was through an improbable chain of events almost 30 years ago that Sierra founder and president Mark Huffstutler found himself in Uvalde running an FBO. And then, almost before he knew it, he was the man behind a series of ever more ambitious aviation ventures, including a full-service maintenance hangar and a busy mod shop. Starting in 1986, Sierra acquired the rights to several modifications packages, including the Citation Eagle and Longwing mods, the well-known lineup of Robertson STOL modifications, and the mods owned by the Dee Howard company, in nearby San Antonio.
Before long, Sierra found itself as one of the handful of companies in the world that specialize in breathing new life into older jets in large part by putting new technology engines on them.
Sometimes it's easy to get lost in the details of a mod package by focusing not on what a program does for the airplane but on how it does it. The end result can't happen without the little details getting taken care of, but what most customers are looking for is the bottom line.
And with the Sierra Citation Super II and Super S-II, those bottom lines are very impressive.
Sierra's Mission: Find New Homes for the Williams FJ44
While Sierra Industries today owns more than 300 STCs, many of them for Cessna Citations, it is safe to say that it wouldn't be the same company without the Williams FJ44 turbofan engine. Developed in the late 1980s as a 1,900-pound thrust engine for the original CitationJet, the Williams powerplant has since gone through numerous growth cycles, each one engendering at least one new and improved Citation along the way. (The Beech Premier I uses FJ44s, as well.)
Sierra's first engine replacement program was for the Citation I. The Eagle 400 swapped out the original Pratt & Whitney JT-15D-1 engines of the 500 with the JT-15D-4 model used in the original Citation II. The airplane also got an increase in max takeoff weight to 12,500 lbs, and the boost in power from 2,200 pounds of thrust per side to 2,500 pounds gave the Eagle 400 much improved climb and cruise speed performance, compared with the stock Citation I.
But it was the introduction of the Williams FJ44 turbofan engine in the 1990s that gave Sierra a launching pad for new programs. The first FJ44 program, the FJ44 Eagle II, certified in 2002, put FJ44-2A engines in the Citation I, making a whole new airplane out of it, with far greater fuel efficiency and impressive performance improvements across the board. Sierra's Stallion mod, which puts FJ44s on a modified Longwing Citation 500 or a 501, was introduced in 2006. In all, Sierra has re-engined nearly 50 Citation I aircraft.
Citation IIs Take Off
Sierra has two programs for Citation II airplanes, both of which offer spectacular performance improvements over the originals.
For those of you who aren't familiar with Citation genealogy, the Citation II was a larger follow-on to the original Citation. Introduced in 1978, the Citation II featured a larger cabin and more powerful engines. The S-II model came about in the mid-80s and for a time took the place of the II -- it's a complicated family tree. On the same fuselage as the II, the S-II featured a new wing and improved Pratt engines.
Those early Citations are remarkably durable airplanes. Sierra has done engine swaps and full refurbs on Citations with more than 10,000 hours on the airframe, and the fleet leader, they told me, has around 25,000 hours and is still going strong. They are very solidly built.
People who don't know the airplanes assume that the Citation II is a relatively small airplane; it's not. With 10 passenger seats and an impressive range, even unmodified, the II and the S-II are substantial and capable business aircraft.
They are even more so after Sierra gets done with them.
The centerpiece of the Citation II engine replacement programs is the Williams FJ44-3A. The engines, as installed in the Sierra Citation Super II and Super S-II, produce 2,820 pounds of thrust each, compared to 2,500 pounds per side for the Pratt & Whitney JT15 engines on the original airplanes.
At an approximate cost of $1.9 million, when you trade in the airplane's serviceable JT15s, the engine swap isn't cheap.
But it does bring big benefits. In addition to being more powerful than the original Pratt & Whitney engines on the original Citation II models, the FJ44-3As feature dual-channel full authority digital engine control (fadec). The fadec makes the pilot's job easier while eliminating the need for thrust reversers. Because the residual thrust with the fadec engines is so much lower, by several hundred pounds in fact, there is no need for reverse thrust for braking. This saves weight, complexity and cost.