The latest Oliver Wyman forecast predicts nearly 70 cargo conversions in 2019, and not all of these will be giant widebodies or even mainline narrowbody freighters. The e-commerce revolution and need for speed in delivering packages has generated an appetite for variety in regional cargo aircraft types of smaller capacity.
These regional jets or turboprops can be either aircraft modified with special cargo doors to load the standard containers shipped on bigger jets or simply be reconfigured to carry bulk cargo in smaller packages loaded through standard doors. Some conversions are permanent while others retain quick-change capabilities. Versions that combine cargo and passenger configurations are also possible.
Generally, the larger regional aircraft are candidates for the most extensive conversions and busier routes. But smaller aircraft, even down to single-engine models, can play a significant role in the expanding networks of time-sensitive delivery operators.
The air cargo market is so strong now that it is looking for small freighters such as Bombardier CRJ200s to serve the remote fringes of the delivery network or to carry small parcels for express-delivery companies like FedEx, according to Brian McCarthy, head of marketing at Precision Aircraft Solutions.
Delio Petohleb, director of sales for Bombardier’s commercial aircraft asset management, argues that all Bombardier models are good candidates for cargo conversion.
Independent shops have developed supplemental type certificates (STC) for converting CRJ100s and 200s into either package freighters or special freighters with large cargo doors. Package freighter and cargo combination conversions of Q300s and Q400s have also been certified. Bombardier itself has developed a new-production Q400 cargo-combi model.
Petohleb says conversion prospects are driven by age and declining values, so typically aircraft about 20 years old are ideal candidates. More than 20 CRJ200s have been converted, and Miami-based conversion specialist Aeronautical Engineers (AEI) looks to convert another 40 into special freighters over the next few years. Petohleb expects Q400s and eventually CRJ700s and 900s will be equally successful as conversion candidates. AEI, Cascade Aerospace and Collins Aerospace are among the companies that are active in Bombardier conversions.
A typical conversion starts with removal of passenger seats and related interior components such as bins and carpets. Next steps depend on the cargo configuration. Cargo combis involve relocating cabin dividers and retaining some seating; package freighters get full cargo interiors, and special freighters add a large cargo door. The process varies widely, with CRJ200 package freighters needing about 4,000 labor-hours, while special freighters require about 130 days of work.
Petohleb believes converted Bombardiers are well-suited to feed the North American networks of delivery companies such as FedEx, UPS and DHL and to serve long, thin routes that traditionally use ground transport in Europe, Africa and Latin America. Q-series turboprops are ideal for short-haul, challenging airfields and hot-and-high environments, while CRJs do best on long, thin routes or operations that benefit from jet range and speed.
Philippe Archaud, head of asset management and freighters at ATR, notes that his aircraft also can be converted to either bulk freighters, with loose cargo loading through the standard front cargo door, or freighters modified with large cargo doors to load standard containers. Currently, AKKA/Aeroconseil, Aerodisa and IPR hold STCs for the bulk freighter, and IPR also holds an STC for the container freighter.
Archaud argues that all ATR 42-300s and -500s and ATR 72-200s and -500s are suitable for cargo STCs. He estimates that 10-15 ATRs will be converted annually.
Conversions require reinforcing floors and modifying cargo doors to open from the inside for bulk freighters. Then lining panels, attachment points for cargo nets and loading systems and other components are added. Archaud says these bulk conversions should take no more than two months, and the objective for container freighters with large cargo doors is six months or less.
Bulk ATR freighters are best suited for the packages and boxes companies such as Amazon ship, while container freighters carry large items such as machine tools and industrial equipment.
Archaud notes the high dispatch reliability (over 99.6%) of ATR aircraft, their fuel economy and wide fuselages, plus the availability of aircraft for conversion. A factory-built freighter, the 72-600F, allows carriers to operate a uniform new fleet, as FedEx has chosen to do, or to exploit conversions of legacy ATRs. “With more than 100 ATR freighters in service, they already account for one-third of the regional cargo market,” Archand says.
Unlike the Saab 2000, the Saab 340 was designed from the beginning as a possible candidate for cargo conversion, spokesman Per Skogsberg says. The 340 came with a Class-E-certified quick-change option from the factory, and eight aircraft were delivered in this configuration. The quick-change option enables a switch between pallet cargo and passenger carriage in less than 1 hr.
In 2000, Saab studied a full cargo conversion of the 340A. The study resulted in a configuration with vertical 9G-certified crash nets, a roller system and new durable cargo liners. Cabin airflow and temperature control were retained to accommodate transport of flowers and animals.
This 340A conversion was developed in cooperation with Canada’s Field Aviation. Saab started with the 340A because it was the oldest type and thus the best candidate for conversion. Certification was achieved in 2002, and the first conversion was completed the same year.
Of 459 340s manufactured, 49 have been converted to freighters. Of these, 14 have been converted using a non-Saab STC, and four of these are 340Bs. The other 35, all 340As, were converted using Saab’s service bulletin. Only four of the 49 have been taken out of service.
Skogsberg says Saab is seeing increased interest in converting its 340s. “We have also sold a few recently, which are in the pipeline for conversion,” Skogsberg says. Worldwide Aircraft Services has just released a Saab 340B STC with support from Saab and based on the 340A service bulletin, thus using the same technical solution. “It’s impossible to predict the future market, but with the Saab 340B conversion available, a whole new segment opens and we expect major interest from the market,” he says.
Conversion involves the usual removal of interior panels, overhead bins, passenger service units, seats, lights, signs and placards, oxygen lines and the rear bulkhead. New temperature sensors and smoke detectors are installed to enable Class E certification for fire detection. A smoke curtain between the cargo compartment and cockpit and a small fire extinguisher are also added. Durable cargo liners, kick panels on walls and ceilings, and cylinder rollers for boxes and pallets are installed. Vertical 9g barrier nets are installed for bulk cargo, but tie- down for loads above 9g is easy using seat tracks. Optional are balsa or aluminum floors and blind windows. Skogsberg estimates conversion takes six mechanics 4-5 weeks or around 1,000 labor-hours, depending on their level of experience.
Saab stresses the Saab 340 freighter’s suitability for many missions, including carrying animals and flowers.
Worldwide Aircraft Services Administrative Director David Vorbeck sees high demand for both Saab 340 and Embraer 120 freighters in the U.S., Central America and Africa. Worldwide holds conversion STCs for these aircraft, plus the Fairchild Metro III.
The company converts only one Fairchild annually but expects to do 6-8 120s and 4-6 340B conversions this year. The process is fairly simple: “We remove all passenger equipment and do all we can to reduce weight, then install the freighter modification,” Vorbeck explains. The latter includes high-impact liners, multiple hard points for net attachments and often an improved floor with rollers. Conversions are usually done during maintenance and require six weeks.
Fortunately, feedstock is plentiful. Worldwide has about 15 340Bs and 15 120s on its ramp.
The converted aircraft often serve islands or remote destinations, carry specialized freight to and from small communities or drop a specific product at a particular plant. Maximum payloads are 6,000-10,000 lb. Vorbeck asserts that his company’s extensive experience enables it to offer the best product in terms of price, durability and maintenance costs.
Conversions extend down to even smaller aircraft. For example, Cessna Caravans fulfill many roles, including cargo missions. The Grand Caravan EX was specifically designed to deliver high payloads on short, unimproved runways, all while providing single-engine economy and simplicity. The new Cessna Denali will have a versatile cabin that can be easily converted from passenger to cargo configuration. The twin-engine SkyCourier will be built in both cargo and passenger variants.
On all these new aircraft, OEM Textron offers a cargo equipment option including window plugs, additional tie-downs, cargo nets, straps and a forward crash barrier. The larger Cessnas can haul payloads up to 900 nm, while the typical Caravan or Grand Caravan EX freighter flies 200 nm with bulk-loaded freight.
Textron says a Caravan freighter’s cargo door can be loaded with pallets on a forklift, and flexible cabins have tie-downs that can integrate into seat tracks, making several configurations possible. The Denali’s larger cargo door enables heavy missions, and the SkyCourier freighter will carry up to three standard LD3 containers, each with 4.5 m3 (159 ft.3) of capacity.