The Company Behind Beautiful Warbird Restorations
by Chuck Cravens
Published in Midwest Flyer – August/September 2018
A talented team of people with a relentless obsession for accuracy, and clients whose mission is to resurrect world-class aircraft to honor those who served and sacrificed, is the recipe that fueled the creation of AirCorps Aviation in Bemidji, Minnesota. In six years, AirCorps Aviation has developed an enviable reputation for premier warbird restorations.
The team of 35 highly skilled technicians, led by founder and general manager, Erik Hokuf, and fellow owners Eric Trueblood, Dan Matejcek, and Mark Tisler, have built an impressive resume of restored P-51 Mustangs heralded as some of the finest examples in the world!
AirCorps’ home in the northern Minnesota community of Bemidji, is not the locale that first comes to mind when thinking of the warbird restoration industry. The northern Minnesota town is better known for beautiful lakes, fishing and lumber than world-class World War II aircraft restorations. “We simply needed a place to call home, and establish and build our roots,” said Hokuf, whose hometown is Bemidji. “Bemidji checked every box and we’ve grown from there.”
Northern Minnesota with its base in mining, manufacturing, and lumber has a foundation of people who still work with their hands. AirCorps Aviation attracts both local people, but also attracts skilled craftsman from throughout the world, most recently Australia.
The maintenance team does annual maintenance and specializes in heavy annuals and major component overhauls. With an expansive knowledge of the makeup of the P-51, the parts team is supporting nine P-51 restorations and numerous repairs throughout the world. AirCorps Aviation maintains so many Mustangs that the backlog of landing gear, hydraulics and accessories coming in for overhaul never seems to diminish.
The fabrication team has built a formidable working knowledge of the Mustang and processes that were commonplace during its design and assembly. The blend of modern and traditional techniques pays homage to the men and women of North American Aviation who proved to the world what America was capable of during World War II. World War II drawings are redrawn in modern CAD/CAM software and parts are remodeled by a state-of-the-art 3D scanner to an accuracy of .0012 of an inch, only to be formed by matched tooling mounted in a 1939 Cecostamp drop hammer.
AirCorps’ approach is redefining restoration by producing a dialogue of shared techniques and information that make the operation of warbirds safer for owners and operators. Parts are fabricated to FAA Parts Manufacturer Approval levels. Once parts are finished and inspected thoroughly, maintaining an adequate inventory ensures that a correct and safe part can be supplied when an operator needs a part on short notice.
The immaculate collection of warbirds at Lenzen-Roe-Fagen Memorial Field in Granite Falls, Minnesota, is the home to combat veteran P-51D model 44-63864 “Twilight Tear,” restored and completed in 2011 for Ron and Diane Fagen and the Fagen Fighters WWII Museum.
The iconic black and white checker nose aircraft of the 78th Fighter Group flying out of Royal Air Force Base Duxford, Cambridgeshire, England motivated AirCorps to dig deeply into research to honor the aircraft and develop new perspectives on restoration.
“It just isn’t in our DNA as a shop to focus solely on the aircraft. I think that is what makes us special as a warbird shop,” said co-owner Mark Tisler. “We share a love for veterans and their stories, and we are fortunate our clients want these stories to be broadcast.
“There is an enormous responsibility when you resurrect the airplane to look beyond the horsepower, armament, and miles per hour. Just think of the flush of emotions that young Twilight Tear WWII pilot Hubert Davis would have felt when he was delivered the P-51 that would carry him into combat.”
Twilight Tear, named after the 1944 thoroughbred horse of the year, would provide the protection Davis and the bombers he escorted needed to survive the war. 44-63864 survived WWII, went to Sweden, Israel, and then to Bill Lear Jr. who used it to test and develop systems that would eventually become the Lear Jet. Damaged in Iceland during a ferry flight, the Fagens commenced the restoration and a completed Twilight Tear eventually retook the skies in 2011.
On July 23, 2011 at 4:00 p.m., the armorer gave the all clear; Twilight Tear’s tail had been elevated and anchored. Six Browning M-2 guns were methodically inspected and installed. The bays were loaded with 1880 rounds of live .50 caliber ammunition. At 1000 inches as per the Mustang maintenance manual, bore sighting had been performed and every precaution checked, double-checked, and triple-checked. The sense of excitement was palpable as the K-14 gunsight reticle illuminated and locked on the paper profile of a BF-109 in the dugout sand trap.
“The unfamiliar sight of a combat veteran P-51 shooting live rounds and tracers sent reverberations through my chest as I pulled the trigger,” said Mark Tisler, who was one of the lucky ones to pull the trigger. “The rounds sent sand flying throughout the sand trap and the tracers were a mesmerizing sight as the smell of gunpowder filled the air. I can only imagine what it would have been like to be in the air in combat.” Twilight Tear was awarded Warbird Grand Champion at Oshkosh in 2011.
The Minnesota Mustang, Sierra Sue II
“It was a fairly simple directive; restore the aircraft to be the most authentic P-51 in the world. That was the goal in returning WWII combat vet, P-51D 44-63675, Sierra Sue II back to its wartime glory,” said Erik Hokuf.
“Every decision from day one brought us closer to the goal of authenticity and completion. Sierra Sue II challenged us to accomplish things never before done and elevate the standard to which we hold ourselves. While we all had experience with big projects prior to Sierra Sue II, this rare opportunity to work on a dream project somehow ended up being our very first major restoration at our new facility.”
The disassembly and subsequent reassembly of one of fewer than 25 surviving WWII combat veteran Mustangs commanded almost obsessive attention to every detail. The 402nd Fighter Squadron, 370th Fighter Group aircraft flew in the 9th Air Force with pilot Robert Bohna at the controls.
Bob Bohna left us an account of his last mission in his diary. Author and brother of “Doc” Christgau, Sierra Sue II’s owner for over 34 years, John Christgau relates the story as Bob Bohna told it to him: “He spotted an ME 262 far off. Without breaking radio silence, he left the formation suddenly. There was no hope of catching the jet, much less getting a good shot at it. Still Bohna laid the pipper of his gunsight on the distant speck and pressed his trigger button. He felt his camera click on, and then Sierra Sue II shuddered as her six machine guns rattled. After weeks of little action, it gave Bohna a rush, even if the bullets went only halfway to the jet.”
By virtue of attention to every detail, Sierra Sue II captures a significant moment in American heritage and is recognized as one of the most complete authentic warbird overhauls in history.
Combat veteran P-51D 44-63675’s restoration by AirCorps Aviation has set a new benchmark in the Mustang community. From varying shades of its natural metal skin to visible Alclad logos and its crude, albeit correct, nose art, the attention to detail is extraordinary.
Sierra Sue II resides at Wings of the North Museum in Eden Prairie, Minnesota, and can frequently be seen flying around the Twin Cities and at airshows around the upper Midwest.
The “Bush Stearman”
Another historically important warbird resides at Wings of the North; Bu 3347 is an early N2S-1 with a special history and a story to tell.
January 28, 1943 was a typical cold Minnesota mid-winter day when the youngest aviation cadet in the Navy walked out to a yellow Stearman sitting on the ramp at Wold Chamberlin Naval Air Station (NAS) in Minneapolis. The mercury hovered at 16 degrees Fahrenheit as President to be, George H. W. Bush, climbed into the rear cockpit for his ninth solo flight of the month.
On July 10, 2015, that very same yellow N2S-1 Stearman, lifted into the air for the first time in many years after completing an extensive eight-month restoration at AirCorps Aviation. All went well and with test flying complete, Paul Ehlen and Mark Tisler made the flight to Oshkosh, Wisconsin from Bemidji with one fuel stop to place the aircraft on display at EAA AirVenture Oshkosh where it was awarded Best Stearman and a Silver Wrench plaque.
Other Facets of AirCorps Aviation
Warbird restorations aren’t the only focus of AirCorps Aviation. Over a period of 60 days in 2017 AirCorps restored, serviced and fabricated parts for 39 different airplanes ranging from a Dassault Falcon 50 jet to a Focke Wulf FW-190. Repairs have also become a major part of the work done at AirCorps including repairs to the CAF Redtail Squadron P-51C when it was damage during its extensive 2016 educational tour.
AirCorps Art, a niche service that provides research and production of correct aircraft markings, has all of the North American factory and manufacturer markings and placards. In 2017, AirCorps Art produced the 600-plus water transfers and external markings for the B-17 “Memphis Belle” that has just been restored at the National Museum of the U.S. Air Force, and the Commemorative Air Force C-47 “That’s All Brother” (see June/July 2018, Midwest Flyer Magazine).
Every warbird has a story and it is those stories that captivate a new generation of warbird restorers, owners, and enthusiasts.
EDITOR’S NOTE: Chuck Cravens is a retired teacher and coach living near Walker, Minnesota, and has put a lifelong passion for aviation to work as the historian at AirCorps Aviation.
Chuck Cravens wrote a book on the history and restoration of Sierra Sue II entitled “Combat Vet P-51, The History of Sierra Sue II, World War II Survivor.” This historical overview takes readers from the factory door in Inglewood, California in 1944, through Sierra Sue II’s combat record with the Army Air Force in 1945, and on to her service with two other nations’ air forces, as well as her rich post war civilian life.
Sierra Sue II’s present story is detailed in the second half of the book which celebrates AirCorps Aviation’s painstaking restoration to precisely replicate her condition immediately after her nose art was painted in Belgium. Also included are original military documents and over 180 photos and engineering drawings to help us understand the story of this rare surviving P-51. The book is available at the AirCorps Aviation website: www.aircorpsaviation.com under the FOR SALE section, or direct by clicking here: http://www.aircorpsaviation.com/combat-vet-p-51-the-history-of-sierra-sue-ii-world-war-ii-survivor.
