The huge oil price rises of 2008 led many observers to predict that the frugal turboprop would rise again to compete strongly with the small jet sector. But since then the price of a barrel has fallen back sharply, and with it any real hopes of new business turboprop development.
Despite this rollercoaster, the turboprop charter sector finds itself in rude health, supplied with new aircraft by two manufacturers exploiting now long-proven models, the Beechcraft King Air and the Piaggio Avanti, and with a large base population of other legacy aircraft types still highly active.
Owners report that the P180 Avanti is popular because of its reliability and operating capability, which has given rise to the term "jet speed turboprop". And all pilots love flying the King Air according to Capt Peter Scott. He manages the Aberdeen base which operates Gama's two King Air 200C on behalf of the Scottish Ambulance Service. "I have never come across anyone who does not think it is a great aircraft to operate. Our latest version with Pro Line avionics, smooth autopilot and flight director makes it a very enjoyable 'office' to work in.
"Dispatch reliability is very good and it does not take too long to receive spare parts, if they are not already held in local store. We are only AOG longer due to spares sometimes having to come up from our maintenance base."
The P180 and the King Air are both favoured for air ambulance work with organisations like Lotnicze Pogotowie Ratunkowe (LPR), the Polish air medical rescue company. It selected the Avanti II after an extensive evaluation process that took into consideration the performance of the original model Avanti air ambulance which was acquired by LPR back in 2004. The company operates air rescue missions from 16 different operating bases. The Avanti II is equipped with Pro Line 21 avionics and LPR says its pluses include high cruising speed and a high loading capacity.
It says: "The P180 Avanti II has an endurance of over 1,700 miles at a speed of 400 kts and a maximum cruising altitude of 41,000 ft. Its overall performance is similar to that of a jet but with 30% less operating costs. It offers passengers a level of comfort matching only that of bigger and more costly aircraft."
But the P180s and the Beechcraft 90, 200 and 300 series are just two of a large number of twin engine turboprops that provide sterling service including the business configured Jetstream 31/41; the Piper PA31T/PA42 Cheyenne; the few BN-2T turbine Islanders and Partenavia/Vulcanair P.68TP; and the Cessna 425 Corsair/Conquest I, 441 Conquest II and F406 Caravan II. Also in service are the business-configured Dornier 328, Saab 340 and Let 410UVP, the Mitsubishi Mu-2 and the turbine variant Twin Commanders.
One F406 operator says he is very satisfied with the maintenance support, dispatch reliability and operating capability and satisfied with the value. "The best aspect is the cargo door and I don't see a worst aspect. The most desirable upgrade is a state-of-the art avionics like the Garmin 600," he adds.
These are typical assessments: turboprops are fuel efficient, robust and good for landing on airfields but the operators have to deal with the problems of balancing investment in modernisation against the aircraft's age.
Many twin-engine turboprops are operated for charter or air ambulance work alongside jets with AirMed, a long established air ambulance company based at the UK's Oxford airport, providing a typical example.
Rapidly approaching its 25th anniversary, AirMed is one of the UK's largest air ambulance providers but also offers passenger and cargo charter.
Rupert Dent, md, says: "We have just become the only UK-based provider of a jet air ambulance with our Learjet 35A coming online but AirMed's fleet of nine aircraft includes a wide range of fleet capabilities with pistons and turbo- props. Apart from the Learjet 35A, the entire fleet is made up of Piper aircraft and includes two Piper Cheyenne IIXLs and two Piper Cheyenne IIIAs."
The first turboprop, a Cheyenne IIXL, was originally added to its fleet in February 2005 and another followed in October 2005. The first Cheyenne IIIA became operational in February 2007 and the final Cheyenne IIIA was online in December 2008. "In this time they have flown a total of 6,500 hours," Dent reports.
AirMed not only owns and operates its own aircraft, but it also has a fully integrated EASA 145 Part M maintenance facility. Dent says this allows the company to enjoy seamless provision of maintenance for its fleet. "Through excellent contacts with Piper and Cessna, AirMed Engineering is also a fully authorised Cessna service and parts facility, it has little difficulty in sourcing the spares required for the Cheyenne fleet."
He adds: "One potential drawback of operating a Piper fleet is that some of the spares are sourced and shipped from the US which can lead to some delays. However due to the integrated facility and AirMed Engineering's developing parts business, a good stock of necessary parts is constantly held at Oxford and delays are infrequent."
AirMed, he says, has found that the Piper Cheyenne is an excellent tool for normal cargo and passenger charter as well as for air ambulance work.
"This is due partly to the fact that their purchase cost is lower than an equivalent Beech 200 but also because they are very economical to run and they can be chartered out at a very competitive hourly rate. Airmed is certainly pleased with the success that it has found with this aircraft type."
The turboprop component of the AirMed fleet has grown not only in size but in popularity with its clients. "There are certainly no plans in the future to remove any of them from the fleet," Dent says. "There are, however, no plans to add any more Cheyennes to the fleet as AirMed is concentrating on expanding and providing UK-based Learjet 35As due to popular demand."
Because so many turboprops are out of production, and existing aircraft will age and get more expensive to maintain, even operators satisfied with their fleets may be increasingly forced to mix and match with jets and newer aircraft.