AM Craft introduces 3D printed arm caps to LOT Polish Airlines 737 fleet
A total of 1200 parts were delivered with EASA Form 1 Airworthiness Certificate
LOT Polish Airlines has begun installing 3D printed arm caps on their Boeing 737 fleet, designed and manufactured by Latvian aerospace AM specialist AM Craft. Poland’s flag carrier is one of the longest-operating airlines in the world, with more than 80 aircraft serving destinations across Europe, Asia, and North America. Keeping this fleet in top condition is a high priority at LOT, but sourcing replacement parts has become increasingly difficult in the aviation market in recent years.
“Over time, components experience wear and tear in a frequently used space like an aircraft cabin,” said Maja Margul, Continuing Airworthiness Junior Specialist at LOT Polish Airlines. “We maintain an inventory of spare parts to ensure timely replacements as needed. However, occasionally, parts wear out faster than anticipated, become unavailable from the original manufacturer, have extended lead times, or require design enhancements.”
That challenge led LOT to seek a new solution for arm caps for the economy class seats on their 737 fleet. The original arm cap was produced in multiple steps with a rubber cap surface attached to an injection molded frame attached to the seat. Over time, the interface between the rubber cap and the plastic frame is degraded and the cap will no longer stay in position on the frame – leading, in the worst case, to the cap coming off in a passenger’s hand. Additionally, the plastic frame frequently breaks where it attaches to the seat. Procuring additional parts from the original supplier became difficult and LOT sought an improved alternative.
AM Craft offered LOT an innovative solution to this problem. The company’s engineers designed a new arm cap as a single 3D printed piece. This eliminated the interface issues between the two parts. AM Craft also redesigned the interface to the seat to reduce the risk of breaking in the location that the previous design had experienced. AM Craft utilized a specialized process of smoothing and painting the outward surface to achieve the expected finish and quality. This also allowed AM Craft to match the exact color of the LOT Polish cabin interior.
“Originally, we intended just to replace the broken arm caps with replacements from the seat manufacturer, but the AM Craft part was such an improvement that we replaced all the arm caps with the 3D printed version,” said Margul.
Since 3D printing does not require the high investment in tooling that injection molding or other traditional manufacturing processes might, AM Craft was able to offer a more cost-effective low-to-mid volume price than a new design that relied on traditional manufacturing technologies would be able to achieve.
“LOT Polish Airlines has a long history of leadership in commercial aviation,” said Didzis Dejus, CEO of AM Craft. “We are proud that we were able to leverage our expertise in design and certification of 3D printed aircraft components to solve their supply chain problem with these arm caps, and we look forward to helping them address additional challenges. For commercial aviation, 3D printing has clearly become a highly impactful technology while no one was looking.”
AM Craft used Stratasys FDM technology and ULTEM(TM) 9085 filament to produce the printed arm caps. Mankiewicz’s ALEXIT coating system was used to color match and cosmetically finish the arm caps.
In total, 1200 arm caps were produced by AM Craft for installation on Boeing 737s in the LOT Polish Airlines Fleet. AM Craft managed the certification of the arm caps and delivered them to LOT Polish Airlines with an EASA Form 1 Airworthiness Certificate.
