Page 79 - 2020 Interconnect Innovations eBook

Evaluating SPE-Enabled Aircraft Weight Reductions and Fuel-Savings
It’s valuable to consider how applying an SPE interconnection solution can reduce aircraft weight and fuel usage. Let’s look at a case for a wide-body commercial jet, such as a Boeing B747-400 aircraft, flying a 5,000 nautical-mile average stage length for 3,000 flight hours per year. If the total weight of all wiring and connectors is calculated to be 1,814kg (4,000lbs), then hauling that mass would consume nearly 60,000 gallons of jet fuel annually. The annual fuel cost value for that amount of fuel comes to $115,800. The annual CO2 emissions from burning that much fuel amounts to 2,785,200kg (1,266,000lbs) annually, which is equivalent to the annual automobile emissions from 124 passenger vehicles.
Calculating the Economic and Environmental Values of SPE in Aircraft
The formula for determining fuel consumption per year is based on the number of pounds of added weight multiplied by incremental fuel burn in gallons per flight hour per pound of weight added multiplied by annual flight hours. For instance, 4,000lbs. of added weight × 0.005 fuel-burn increment × 3,000 flight hours = 60,000 gallons of jet fuel burned.
A valuable free resource for calculating the effects of added weight on fuel burn is the Federal Aviation Administration’s Benefit-Cost Analysis documents, which provide guidance for project-level benefit-cost analysis for capacity-related airport projects, as well as basic guidance for economic analysis of investments and regulations subject to FAA decision-making. The following values for a Boeing B747-400 aircraft are taken from Table 6-1: Large Commercial Aircraft – Incremental Fuel Burn (page 6-7) in Subsection 6.3.1: Incremental Fuel Burn (page 6-6) of the Economic Values for FAA Investment and Regulatory Decisions Guide.
Fuel Cost Value is calculated by additional fuel consumption per year multiplied by the average 2019 jet fuel cost (e.g., 60,000 × $1.93 = $115,800 annual fuel cost).
Annual CO2 Emissions are calculated by gallons of jet fuel burned multiplied by pounds of CO2 emitted per gallon of jet fuel burned (e.g., 60,000 gallons × 21.1 pounds of emissions per gallon = 1,266,000 pounds of annual CO2 emissions). The value for CO2 emissions for jet fuel is taken from the U.S. Energy Information Administration’s table of Carbon Dioxide Emissions Coefficients.
Equivalent of Automobile Emissions was determined by using the U.S. Environmental Protection Agency’s Greenhouse Gas Equivalencies Calculator, which translates 1,266,000 pounds of CO2 emissions into annual emissions from 124 passenger vehicles.
Of course, only a fraction of all aircraft wiring is Ethernet cabling. In this case, it’s estimated to be 5% (100kg or 220lbs) of total wiring. Actual weight will vary depending on the design of the Ethernet network and related interconnects.
If an SPE connectivity solution reduces Ethernet wiring weight by 50%, that will reduce the load by 50kg (110lbs). Eliminating that weight would cut annual fuel consumption by 1,650 gallons (110 lbs. × 0.005 fuel-burn increment × 3,000 flight hours = 1,650 gallons of jet fuel burned annually) and save $3,185 per aircraft per year at the 2019 average jet fuel price. Given a constant fuel cost and a typical 30-year aircraft lifespan, the lifetime fuel savings equals $95,535, which translates to a lifetime reduction in CO2 emissions of 1,044,450 pounds (1,650 gallons × 21.1 pounds of emissions per gallon × 30 years), or the equivalent of taking 102 passenger vehicles off the road for one year.
Lighter-Weight Interconnects can also be applied to trim pounds. A family of EWIS-compliant rectangular connectors is available that provides a robust solution in a small envelope that is 41% lighter than typical D-sub connectors. This weight reduction can eliminate up to 20kg (44lbs) or more per plane, depending on the network’s configuration and other aircraft applications. The weight savings is largely due to a connector shell constructed from rugged materials with strength similar to steel but 40% lighter. The combination of composite materials and machined contacts allows for operation in temperatures extending from -55°C (131°F) to 175°C (347°F), which is suitable for aircraft cabin environments.
Termination Time-Savings is also significant. Compared to a typical quadrax connector with a termination time of 15 to 20 minutes per pair, terminating with a connector optimized for SPE can take just two to five minutes, which is nearly 70% faster. More importantly, the single pair of wires makes terminations both less complex and error prone.
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