In the world of high-stakes defense contracts, its not unusual to see the military say one thing and do another. But when the Air Force selected the British-made Slingsby Firefly to replace its aging fleet of Cessna T-41s six years ago, even some industry insiders were baffled.
Slingsbys initial entry was so wide of the contract specifications-it was 50 knots slower than specified and had fabric control surfaces, a throwback to the Air Forces biplane days-that it wasnt even flight tested against other aircraft from Mooney, Stoddard-Hamilton, Saab and SIAI Marchetti.
Yet in one of the greatest come-from-behind stories in light aircraft history, Slingsby feverishly re-worked the airplane, installed a larger engine, teamed up with Northrop and snagged an Air Force order for 110 new trainers, plus spares, right out from under the noses of the other companies.
Within a year of the first delivery in 1994, the T3A had posted a sorry operational record. It was plagued by frequent, inexplicable engine stoppages on the ground and in the air and its propensity to depart controlled flight with little provocation prompted the Air Force to restrict the T3A to little more than a touch-and-go trainer, not the full-blown aerobatic workhorse it was intended to be. Students who soloed the old Cessna T-41 in 11 flights, required 18 to safely master the Firefly.
Worse, the engine stoppage problem defied solution and three fatal accidents within 18 months led to grounding of the entire T3A fleet, pending a broad Air Force review of the program. As we go to press, the fleet remains parked, with no solution expected until May of 1998.
What follows is the story of the Slingsby Firefly, a program that has gone seriously awry and whose problems came to light when the staff of our sister magazine, Light Plane Maintenance, was asked by officials at Edwards Air Force Base to consult on the T3As engine problems.
Interestingly, the civil GA connection here is that unless the Air Force finds an acceptable fix, Mooney, Stoddard-Hamilton and others may yet get another stab at the trainer plum. In Mooneys case, that would spin off a dandy two-place sport cruiser. (See page 22.)
A New Trainer
The T3As were bought as part of the Air Forces Enhanced Flight Screener program and not, technically, as trainers. By giving them a taste of how the Air Force flies, the flight screening program was supposed to cull candidates with no aptitude for piloting and thus would, theoretically, save the Air Force money by reducing the washout rate.
The new trainer would be flown from the Air Forces contract site at Hondo, Texas and from the U.S. Air Force Academy at Colorado Springs.
At the outset, some Academy instructors objected to the plan, reasoning that only 30 percent of pilot candidates go into fighter aircraft, making acquisition of an over-the-top aerobat unnecessary.
A common question at the time, says former Air Force Captain Richard Hartlaub, was Why are we spinning students during flight screening? The airplane was simply a screener to determine who qualified to enter undergraduate pilot training (UPT) after graduation from the Academy.
Hartlaub instructed in the T3A at the Air Force Academy, as did his wife Kim. He recently left the Air Force, in part because of his disgust with the Firefly program.
Despite objections from the ranks, the Air Force issued a request for proposals to major aircraft manufacturers through standard Air Force channels, listing the requirements the new airplane should have in order to compete for the contract.
Six companies proposed fly-off entries, including Schweizer, Saab, Stoddard-Hamilton with its Glasair III, SIAI Marchetti, Mooney and Slingsby, a relative unknown in the U.S. but a familiar name in Europe, mainly for gliders.
As they usually do, the Air Force contract listed specific performance requirements, having to do with speed, roll rate, climb capability and, one unusual requirement, resistance to potential hail damage from the storms common in Texas and Colorado.
Further, the entries would have to meet FAR Part 23 certification requirements which, as Mooney engineer Tom Bowen says, was something else entirely and somewhat unusual for a military spec.
And, as is often the case, none of the aircraft entered in fly-off met Air Force specs right out of the chute. The Saab Safari was shy on cruise speed and the Mooneys roll rate was a 1/2 second slower than the six-second maximum specified by the Air Force.
But the real shocker was that the Slingsby entry, its T67M with an 200 HP IO-360 Lycoming purpose-built as a trainer, didnt meet the specs closely enough to even be test flown against the others.
Despite the fact that Mooney and Schweizer were willing and able to make modifications and try again, they were kept in the dark about the results of the fly-off.
Yet at one point, during testing at Wright-Patterson Air Force Base, Mooneys Bill Craig was told by an Air Force colonel that this project is yours to lose. Craig figured the real competition would be from Marchetti, not Slingsby.
While Mooney, Schweizer and the others cooled their heels, Slingsby feverishly reworked the T67M, installing a 260 HP AEIO-540 Lycoming and performing other tweaks to meet the Air Forces wants.
Quite to everyones surprise, the T3A emerged from Britain, with a fresh CAA type certificate that would, theoretically, at least, meet FAR Part 23 requirements.
Yet with its fixed gear, the new T67M260 (later T3A) was still 50 knots slower than the 180-knot Air Force requirement and Mooneys Craig questioned how we’ll the Slingsbys fabric control surfaces would stand up to hailstorms. (According to documents obtained by LPM, this contract requirement was mitigated to allow the T3A to pass the Air Forces muster.)
Firefly Wins
In the end, Slingsby won the contract, despite the fact that Schweizers bid was $3 million lower and Mooneys was more than $6 million less than British companys offer. In all, 110 airplanes were delivered, beginning with the Air Force Academy in February of 1994.
Then the trouble started. Since its introduction, there have been more than 50 ground and air engine stoppages, mostly when the power was reduced for landing or for maneuvers. The Air Force reported engine stoppages just after start-up and before taxi, regardless of whether the engine was hot or cold and regardless of what actions the pilots took to keep the engines running.
Figuring the problem was related to vapor lock, the Air Force cut louvers in both sides of the lower engine cowl. Because the engine was equipped with an automatic mixture control, some in the Air Force believed the problem was with the servo and ordered replacements for the components that were presumed defective.
This action began almost immediately after the airplane was placed in service, along with multiple mixture and idle adjustments and replacement of the flow divider cut-off spring.
Regardless of how the operational anomalies were addressed, the T3A engine continued to run rough and exhibit erratic behavior. No amount of pilot input seemed to help. Electric boost pump activation, mixture-control inputs and jockeying of the throttle had little effect on the engine. Occasionally, the engine just quit without warning; no pilot response would bring it back to life.
In response, the Air Force awarded a $10 million contract to Science Applications International Corporation (SAIC) to find and fix the Slingsby problem. Slingsby performed flow tests on the servo while Baylor University and SAIC personnel in Texas, under contract, began testing a fully instrumented and newly refurbished T3A.
No expense was spared; an all new engine and new accessories were used in the flight test. The goal was to measure inflight parameters for fuel system pressures, temperatures and flow rates. Many in and out of the program pointed fingers at the engine and Lycoming was grilled on the performance of its aerobatic IO- 540.
Bubbles in the Gas
When Slingsby installed the six-cylinder powerplant in the newly designated T3A, a new engine mount had to be configured to accommodate the larger size and weight. The LPM staff noticed this while visiting the Air Force Academy. Of prime interest was the firewall-mounted electric fuel boost pump, which is high on the firewall, requiring sharp bends in the fuel lines. Slingsby officials say the pump wasnt moved from the earlier versions but they cant explain why its so high in the firewall. (Most pumps are mounted as low as possible.)