Despite claims that manufacturing in North Carolina is in a death spiral, aircraft-related production continues to grow at an ever-increasing list of companies, including GE Aviation, GE Honda Aero Engines, HondaJet, Spirit AeroSystems, BE Aerospace, MX Aircraft, Allegro LSA, Twin Commander Aircraft, Atlantic Aero, Preceptor Aircraft, and probably a few others I’m not aware of. While many of these firms are headquartered elsewhere, a few are home-grown, for instance Aero Accessories and Marvel-Schebler of Gibsonville, N.C.
According to its website Aero Accessories, “overhauls, develops, produces, and supplies hard-to-find parts for older aircraft, as well as for the newest.”
While this company is not (yet) a household name in aviation circles, the line of products it offers under the Tempest trade name sure are, for instance Tempest spark plugs and oil filters. The name of Marvel-Schebler carburetors, of course, goes back just about as far as general aviation.
When Konrad Schoen, “Mr. Carburetor” of our Bear Creek Aero Club, suggested we contact Marvel-Schebler regarding an overhaul of the MA4SPA updraft carb that came with our Stits SA-7D Skycoupe’s Lycoming O-290-D engine, I saw an opportunity to tour the company with other members of EAA Chapter 1114. A few phone calls were all that was needed to make arrangements, and 12 members found their way to the Aero Accessories and Marvel headquarters for what was to be a fascinating four-hour tour.
We were shown four separate facilities in Gibsonville, where Aero Accessories produces a growing list of replacement parts for Bendix and Slick magnetos, all-new dry air pumps and vacuum regulators, fuel pumps, oil filters, and spark plugs. We also toured Marvel-Schebler, where new, overhauled and rebuilt carburetors are produced.
Aero Accessories has developed its own lines of products, but in some cases it acquired products from others. For instance, its Tempest spark plugs were originally produced under the Autoline brand name, best known for its voluptuous moniker, “Autolite Annie.”
While many brands suffer from a change in ownership, Aero Accessories strives to improve all of its products, rewarding the company with a steady increase in market share. As Mark Lutterloh, plant manager for Tempest oil filters and spark plugs explained, “Since acquiring machinery from Purolator’s Fayetteville facility when they left the aircraft oil filter business six years ago, we have been able to increase our market share against the competition every year. We started with a production rate of about 3,000 filters per month; we now make more than 15,000.”
Amid the hustle and bustle of the busy shop floor, Lutterloh showed us the company’s latest product, a Tempest replacement oil filter for Rotax 900-series aircraft engines. Our chapter’s Techncial Counselor Terry Gardner, a licensed Rotax repairman, immediately pointed out an improvement over the original filters, a welded tab for safety wiring that is common to filters for other engines, but is not included on the filters as they come from the Rotax factory in Austria.
Tim Henderson, Aero Accessories’ founder and owner (pictured below), provided a tour of the magneto and dry air pump facility, which is also the company’s headquarters. He described how a thorough study of the dry air pump line they began working with some years ago revealed a number of potential improvements, foremost among these recountouring of the pump housing’s internal walls to reduce high transient loads on the pump’s blades.
As a result of this and greater attention to precision and testing, the company has been able to reduce the early 1990s warranty rate from 6% at its previous producer to only 0.2% today, he said. Each blade of every pump is individually inspected and fitted, and the entire pump is tested under realistic conditions, according to company officials. A significant percentage of new pumps are also completely dissasembled and checked again after the initial test. The most notable improvement is the ability to inspect the pump during its service life by using the patented “W-I-P“ (wear indicator port).
Henderson demonstrated his famous wit by describing a special gasket created for air pumps. “The oil filter on some engines is located just above the air pump. When the filters are replaced, spilled oil would sometimes enter the vent holes in pumps and affect the dry lubricant. We designed a special oil diverter to prevent this from happening, and called it the ‘LRT’ — Little Rubber Thing.”
Henderson later described how the company got started and how he had some fun with its skeptics: “We were rebuilding magnetos and decided we could improve on some of the replacement parts others were making. When we started selling our new parts, a competitor called the FAA to complain, telling them that ‘some yahoos in North Carolina claim they have PMA approval to make magneto parts.’“
The FAA confirmed this, to their surprise, and later reported the complaint to Henderson, who promptly added a special message to the bottom of every box of these parts that leave his factory: YA-HOOS-NNC.
My special interest was a visit to the Marvel-Schebler facility, located in downtown Gibsonville, which has a lovely Mayberry-like, old-timey charm complete with a rail depot and red caboose. Marvel-Scheber, an independent company, is owned by Mike Allen and Tim Henderson.
Mike Wendtland, better known as “Mr. Marvel-Schebler,” was our host (pictured left). Wendtland has been with the product line since 1991 when he left the Navy, having previously served on the USS Kitty Hawk as an avionics specialist with an EA-6B squadron. Arguably the greatest asset that Marvel-Schebler acquired with these products, Wendtland modestly claimed that he has probably helped produce, overhaul or rebuild “a couple hundred thousand” carburetors in the past two decades. He showed us numerous before-and-after examples of two of the company’s most popular products, the MA3SPA and MA4SPA carbs, as well as the company’s unique flow bench, where carburetors can be tested under realistic conditions. Tests on this system, believed to be one of only two in existence, are offered by the company free of charge. This is one of the reasons that the “new” Marvel-Schebler Aircraft Carburetors company is quickly re-establishing the venerable Marvel-Schebler name to its past glory after continuous predatory lawsuits caused the product line so much damage under its previous ownership that they quit building carburetors. As Wendtland explained, “I have most of my life tied up in these carburetors, so I want to deliver the best products possible.”
While Marvel-Schebler manufacturers and rebuilds many new carbuertors for OEM engine builders, in most cases, an overhaul is sufficient to return a customer unit to near-new specifications, he noted. When this is not possible, parts are replaced as needed and the customer receives a rebuilt unit that meets new carburetor specifications. Wendtland explained that, ideally, a customer will exchange his existing carb, receiving a core credit and a new unit built from a core already in-house. This way, turnaround is limited to just a few days. We were all relieved when Wendtland called the condition of our Skycoupe’s MA4SPA “about average,” and he offered to give it his own personal attention during overhaul.
While I chose to stay in the Marvel-Schebler facility to discuss our options with the carburetor, most of our group moved on to the last facility in town where Tempest spark plugs are made. From reports I received from others, this was the most technologically advanced and automated of the impressive facilities toured. The company touts the advantages of the Tempest spark plug over the competition, citing monolithic engineered resistors, a one-piece, fused-center electrode/resistor, high conductivity copper core, and a proprietary glass center seal.
One word comes to mind on having seen the high-tech aircraft parts created within Aero Accessories’ Gibsonville facilities. As fellow Tarheel Gomer Pyle would have said: “Shazam!”