On the surface it sounds relatively straightforward. Boeing is converting ex-airline DC-10s to freighters for FedEx, and for any other operator that wants it. The real story is quite different in terms of scale, timetable and technical challenges.

"It's been an enormous undertaking," says Boeing MD-10 deputy programme manager, Jack Jewell. "We basically started from scratch in September 1996 and, over the last 18 months, the operation has grown tremendously," he says. The conversion is so fundamental that the DC-10s will in future be classified as MD-10s under an amended type certificate.

The MD-10 programme is made up of two main phases. The first encapsulates the basic passenger to freight conversion, a heavy maintenance check, refurbishment and restoration, and a thorough standardisation effort to bring each aircraft in line with latest service bulletins.

The second phase is focused on the installation of the two crew advanced common flightdeck and a raft of reliability improvements. All the ex-passenger DC-10-10s will undergo this modification, while FedEx's existing DC-10 freighter fleet - 14 DC-10-10Fs and 23 -30Fs - will also be upgraded progressively with modification work extending out to 2004.

The passenger to freighter conversion work is performed in five main modules, some of which can be omitted depending on the build-standard of the basic aircraft. Module one involves modifying the main deck floor and installing pallet handling and smoke detector systems. The extent of main deck floor modifications depends on the age of the DC-10, with more work required for early vintage models. All variants, including, to a slight extent, even the MD-11 passenger to freighter conversion, require module one. The second module, which involves strengthening the centre wing box/floor support area, applies only to DC-10-10s.


ANCRA International, the California-based cargo system specialist, supplies the main deck cargo handling system that builds on modules one and two directly to FedEx. This consists of omni-directional ball-mat panels in the door area, side guides, locks and rails. "We've also modified it to make it lighter and easier to handle," says ANCRA business development manager, Martin Bleasdale. The new system incorporates overrideable guides that will allow FedEx to operate the MD-10 in four different configurations: package freight, cargo charter, US military charter and FedEx "heavy" freight.

Module three, says Jewell, "-is the biggest of them all", and covers the installation of the main deck cargo door. This upward-opening fixture, measuring 2.6m high x 3.5m wide, was originally designed to be built on to the airframe in situ. "We either use a 'spider tool' to cut a hole and build a door on the fuselage, or we have a modular tool which we use to make a door off the aircraft. Then we put it in a cradle and mount it," says Jewell, who adds that the latter is preferred.

Module four involves replacing the passenger interior, fittings and systems with a freight interior, modifying the air conditioning system and installing a cargo barrier net and fittings. FedEx has opted for a rigid cargo barrier which is capable of sustaining 4g loads and gains an extra 1,520mm in crew rest space. In aircraft fitted with the flexible net, this area has to be kept empty in case the barrier "bulges" into the zone in the event of an accident. The rigid barrier, developed in association with Californian company Tolo Aerospace, also provides positive smoke and fire containment, adds Jewell. A quick access door is built into the side of the barrier and the extra room is occupied by four additional courier seats.

The fifth module covers conversion of the lower galley compartment to a full cargo compartment. "Aircraft with lower galleys need more work and more reinforcing than those with upper galleys that are better aircraft to modify," Jewell says. Of the roughly 308 DC-10 passenger aircraft estimated by Douglas Products Division to be in existence, some 94 have the lower galley. These include 55 DC-10-10s, five -15s, 11 -30s and 23 -40s. With its purchase of the American Airlines and United Airlines fleets, the bulk of the -10s have been accounted for by FedEx, though Boeing believes the -30s will prove just as attractive to the freight market in the long term.


The big changes that set aside the MD-10 programme from any previous cargo conversion effort reside in the flightdeck. The advanced common flightdeck (ACF) that has been designed for the MD-10 goes a step beyond the MD-11 and, in theory, will be more up to date than even that of the 777.

Like the newly developed 717 flightdeck, the ACF is built around Honeywell's Versatile Integrated Avionics (VIA) 2000 suite, and it allows the MD-10 to be operated by two crew members rather than the DC-10's normal complement of three.

Three VIA 2000 processes form the heart of the system, which externally replicates the flightdeck of the MD-11 with six main display screens arranged side by side across the cockpit. Although identical in size to the 200 x 200mm units of the MD-11, the MD-10 will use Honeywell flat panel display units like those developed for the 777.

The VIA units provide greatly enhanced functionality, allowing the current DC-10 flight data acquisition unit and central aural warning system to be housed within the same processor. The VIA-based architecture replaces all the conventional wire in the nose and replaces ARINC-500 series navigation radios with current generation sensors.

The scale of the changes, particularly to the flightdeck, are the main drivers behind the far more rigorous certification requirements being demanded by the US Federal Aviation Administration. The FAA has made known its increasing aversion to the use of "grandfathering", and the MD-10 is seen as something of a test case within the certification community.

"The basic passenger to freighter conversion is not a big deal, but the ACF is - because of all the major changes to the flightdeck," says Jewell. "The requirements are going to be rigid, but we've done our homework to meet them. Because we have the MD-11 and 777 behind us, we think there should not be a problem getting the MD-10 certificated," he adds. Boeing is going through the requirements "up front" with the FAA, a process began by McDonnell Douglas, to ensure no last-minute surprises of the sort than caught out the Next Generation 737. "The conversion will be cleared under an amended type certificate, not an STC [supplemental type certificate]," he adds.

Phase two also includes a wide range of other system improvements aimed at boosting dispatch reliability by at least 1.5%. These include provision of a Rockwell Collins RTA-4B weather radar with forward looking predictive windshear warning, Traffic Alert and Collision Avoidance System (TCAS II), AlliedSignal Mark V ground proximity warning system and a six-channel satellite communication and global positioning system. Improvements will also be made to the electrical power system, tail-scrape proximity device, auto-throttle clutch and engine cowl anti-ice valve. As part of the drive to improve dispatch reliability, the MD-10 will also be fitted with an on-board maintenance terminal.

Due to the extent of the ACF work, Boeing plans to use three MD-10s in the certification programme. The first aircraft, an ex-United DC-10-10 (N1821U/fuselage number 138), has arrived at Long Beach having undergone a maintenance check. The aircraft is about to be disassembled in preparation for fitting out with Module Four of the freighter conversion and the first ACF.

Flight tests will begin with the first aircraft, T-1, in the third quarter of this year, with certification targeted for December 1999, says Jewell. Two more test aircraft, T-2 and T-3, are also scheduled to join the certification programme. T-2 will be a DC-10-30F (N316FE), the first -30 to be involved in the MD-10 programme, which will be pulled from service with FedEx and be delivered to Long Beach in January 1999, at about the time that T-3, another ex-airline -10, will arrive following freighter modification. Flight tests are expected to be based at either Yuma or Williams gateway airports in Arizona.


While the certification effort winds up in the USA, the first flightdeck conversion line will begin spooling up in Zürich, Switzerland. SR Technics, an SAir Services company, was awarded the first contract in March and will convert at least 15 aircraft from 2000 to 2002. SR Technics also holds options for up to 10 more MD-10 conversions. The first production line ACF is expected to be handed over to FedEx as early as January 2000. In the meantime, Boeing says it will go out for bids for others like SR next year.

While the ACF phase of the programme progresses, the likelihood is that the basic passenger to freighter conversion effort will have spread to include new sites. Initial work was started at Aeronavali in Venice, Italy, in the second quarter of 1997 and, by November, the first aircraft (ex-N1827U) had been handed over to FedEx. Of the first 25 MD-10s on firm order from FedEx, some 14 were earmarked for conversion by the Italian company.

Eight of the first batch were allocated to Dimension Aviation, at Goodyear, Arizona while one was sent for conversion to Mobile Aerospace (part of Singapore Technologies) at Mobile, Alabama. This company also holds options on a further nine.

New sites being considered for future MD-10 passenger to freighter conversion work include the former US Air Force base at Kelly, Texas, which Boeing recently acquired as an overhaul and maintenance site. "There are no firm plans today, but it would be a good candidate," says Jewell.

The search for new sites gained momentum as FedEx began increasing its commitment. Following its initial order for 25 aircraft, it later increased this to 35 and added its fleet of 35 DC-10 freighters (23 -30s and 12 -10s) to the ACF conversion plan. It therefore has firm orders for 70 MD-10s, plus options on a further 50. With interest over the MD-10 growing within wider freight circles, it is now guaranteed that the DC-10 will follow the lead of another venerable Douglas product, the DC-8, and go on to enjoy a new lease of life as a freighter.

Source: Flight International