KC-135 and digital engineering come together to save time and costs

Boeing engineers will digitally model horizontal stabilizers to sustain the Stratotanker for decades to come

A row of U.S. Air Force KC-135 tails from the Iowa Air National Guard on the ramp at the Iowa Air National Guard’s 185th Air Refueling Wing in Sioux City on October 3, 2019. U.S. Air National Guard photo by Senior Master Sgt. Vincent De Groot

As the U.S. Air Force ushers in a new era of aerial refueling with the KC-46, Boeing KC-135 engineers are using digital engineering to sustain the aircraft for continued operations. Advanced technology has brought about a new era of designing aircraft and engineers of today will rely on engineers of yesterday to keep the Stratotanker flying for many years.

Exemplified through its Mission Accelerator portfolio, Boeing is leveraging innovative digital processes to enable product development to be faster, more cost efficient, and achieve higher levels of first-time quality. However, how do you use this process on an aircraft predating the technology and initially designed on mylar? Simply put, you transfer full-scale, hand-drawn horizontal stabilizer blueprints into a three-dimensional model.

“Our team will take two-dimensional engineering of the horizontal stabilizers from nearly 70 years ago and remaster the design, bringing it up to modern design standards,” said Jared Rodgers, KC-135 engineering manager at Boeing. “For us to accomplish this, we will transfer these drawings into three-dimensional space allowing the use of a hybrid model-based approach for design and manufacturing.”

The mylar blueprints require an environment-controlled room to accurately scan them into three-dimensional software programs, states Rodgers. He points out where extra pixels appeared on blueprints from decades of being rescanned and it is the team’s ambition in ensuring these inadvertently-added elements are removed in the transfer.

“The initial KC-135 engineers were meticulous in drafting and used cross-sectional templates to define part shapes,” said Rodgers. “As the original engineering data ages and is revised over the years, drawings become hard to read and our team will utilize digital loft data combined with high accuracy drawing scans to better reflect the original intended engineering definition.”

The KC-135 on the Oklahoma City Air Logistics Center periodic depot maintenance line in the late 1950s. Photo: U.S. Air Force

Rodgers mentions the team can remedy many drawing issues early, leading to improved quality, reduced misinterpretation by suppliers, and minimal rework.

In March, Boeing was awarded the horizontal stabilizers contract and Rodgers’ team will need to deliver 34 shipsets, with each consisting of the left and right stabilizers as well as the center section. The team will need to digitally reproduce more than 2,300 parts through model-based engineering.

From this extensive effort, Rodgers states this newly-developed three-dimensional engineering creates the start of the digital sustainment thread. With this information the data provided to supplier is more accurate, thus reducing errors in manufacturing. Additionally, the data can be shared seamlessly to maintenance crews, making final assembly, installation, technical order production and maintenance training easier and more effective than ever before.

“The skillset needed to design new aircraft parts in three-dimensional space versus making a twin from initial engineering are completely different,” said Rodgers. “We are in exciting times and to be the team bridging these eras is truly remarkable.”

Work is expected to last through 2028.