Fast 5: Designing A 100+ Ton Freighter Conversion

Three companies are seeking to covert the “Big Twin,” the Boeing 777, to cargo configuration. Jim Gibbs is president of one of these companies, the Kansas Modification Center (KMC). Aviation Week spoke to Gibbs about KMC’s challenges during its 777 cargo conversion project and when the freighter is expected to be certified.

What were the hardest design challenges that had to be made on the 777 cargo conversion project?

From the beginning, KMC started the conversion project by focusing on door placement. After an arduous study with input from both customers and a substantial amount of non-recurring engineering, we discovered that not only is the location of a front cargo door advantageous and obvious from an operations standpoint, but the significant weight savings associated gave all the more reason for a front cargo door.

Reducing operating empty weight to increase payload has always been a focus of KMC's 777-300ERCF program. Every design and manufacturing decision is made with weight conservation in front of mind. From replacing the carbon floor beams with newer alloyed aluminum beams, to installing a rigid, yet ergonomic, 9G barrier and cargo door, KMC has made weight savings a focal competence in our designs.

What is the advantage of the large cargo door forward of engines on your KMC 777 conversion?

With its forward door design, KMC’s B777-300ERCF freighter saves up to 7,000 lbs. compared with aft-door designs. Assuming 4,000 annual flight hours, it is projected to consume 205 lbs. per hour less fuel than a conversion using an aft door. Assuming fuel at $6 per gallon, that translates to saving $660,000 a year and $10 million over 15 years. It also increases payload revenue on longer routes. And having the main cargo door forward of the wing brings cargo-loading, operational and safety advantages.

What types of non-technical challenges have you experienced with the conversion program?

The FAA regulatory environment has always been one of rigorous oversight. Moreover, post-737 MAX, all countries' aviation authorities have a heightened focus on fly-by-wire aircraft, which is what the 777 is. An STC [supplemental type certificate], such as for our conversion on this aircraft type, requires integrated cockpit interfaces and changes to the flight systems to manage loads and flight characteristics. KMC has full understanding of all the Honeywell equipment that is the brains of the 777-300ER. We have determined that the safest way to the highest payload and lowest operating empty weight aircraft is to certify to Boeing’s type certification data sheet, which has limitations on gross weight and maximum air speed. After STC approval, KMC will continue to improve the 777-300ERCF's payload capabilities via an increased maximum zero fuel weight.

Have supply chain issues impacted the program?

In today's dysfunctional global economy, raw materials have been a very significant issue, not only to us at KMC, but to all aerospace manufacturers. Obtaining the alloys necessary for manufacturing can lead to delays or, worse, to work stoppage. I come from a machine shop background and have realized that the vendor list and maintaining our delivery and slot dates is of utmost importance to be sure we deliver on time.

What is the status of your certification efforts on the 777 and when would you expect or hope for certification?

This year will be a year of important milestones for the KMC 777 P2F program. The program expects in 2023 to receive FAA approval for its project certification plan (PSCP). This is significant because the PSCP is the roadmap to achieving FAA certification. The plan contains several hundred pages of detail, typically takes 12-15 months to gain FAA approval and [takes] three-plus years from the date of filing to certification of a freighter conversion. PSCP filings become public record, and we think our most recent search of these records position the KMC program favorably when considering the other 777 freighter conversion options that are available.

KMC is planning to deliver its first 777-300ERCF in the third quarter of 2024.

Credit: AviationWeek - Henry Canaday