The King Air Rebuild of the Century
aka King Air 90 Saved from the Scrapheap!
It’s not every day that one gets the opportunity to work on a complete King Air Rebuild. Nor is it every day that you see a wingless King Air 90 transported down Las Vegas Blvd. The trip from McCarran to Apex Aviation at Henderson Executive Airport was just the first small step on a several-month-long road to recovery.
The aircraft we were about to save had experienced a gear-up incident while landing at McCarran Airport. When we found out about it on the local news, our Maintenance Manager went over to McCarran and dropped off his business card. Shortly after that, the customer contacted us to see what we could do. The preliminary plan was to do an initial assessment at McCarran, remove the wings, transport the aircraft to Apex Aviation at Henderson Executive Airport, and perform a closer evaluation.
Several of our technicians went to McCarran for the pick-up. After they de-fueled the aircraft and removed the wings, the aircraft recovery company we hired picked up the airplane fuselage and wings and put it on a flatbed with the engines still installed. We formed quite the eye-catching procession down Las Vegas Blvd. with a pilot vehicle both in front and to the rear of us.
Apex Aviation was hired to determine if the aircraft was beyond economic repair, to identify the issues, consult with manufacturers, locate parts, get estimates, make repairs, install and rebuild as necessary.
Have you ever wondered what goes into a rebuild job like this? Well, wonder no more. Let us begin.
The extent of the damage was not readily visible at first glance and unfolded as we got deeper into the project. When we initially looked at it at McCarran, we knew at the least we would have to repair/overhaul the engines and replace the propellers. We also knew that there was belly damage. But once we got into it, we found quite a bit of other damage because when the landing gear hit the ground, they were in transit.
We consulted the owners and the insurance company every step of the way for decisions. King Air expert Lou Taylor led the maintenance team, which included Joel Woolfenden, Rob Skibinski, and Fred Beamer. Joel, Fred, and Rob were responsible for the incredible sheet metal work.
There were many dependencies in this project; many things couldn’t be done until something else was completed first. However, due to the extent of the damage, we had many concurrent sub-projects.
The initial step of the entire repair process was to contact Textron engineering about shoring up the fuselage. Once it was shored up, and in position, we mounted the wings back on to the fuselage. Once the wings were mounted, and everything was secured, we were able to set it on its landing gear and then shore it up again, making adjustments so that it stayed straight while we repaired the belly.
The aft belly was a major project. We provided the engineers at Textron with pictures of all that was damaged, and they gave us an in-depth repair scheme based on all the information we had supplied to them.
As we worked the repair on the belly, we removed the engines and sent them out to be evaluated.
It took quite a while to do the belly repairs because there was extensive damage.
We wound up cutting out a five-foot by four-foot section of the belly that was shredded and repaired it using the repair scheme provided by the manufacturer.
There were six bulkheads, six frames, and four rows of stringers that had gotten damaged. While we were able to procure the stringers, we weren’t able to acquire the frames. Per the repair scheme, we could either take a frame and cut it to match or we could make our own, so we made our own frames.
It took care and diligence to get the frames perfectly lined up to the airframe that existed. First, we cut it all away, then assessed it and conducted another inspection, checking for cracks, hidden damage, and anything else we might have missed on the first inspection. That became the routine for every section.
Part of the build process was getting the old stringers out, getting the new stringers in, forming the ribs, and then checking the fit of the skin on the exterior.
All of these fabricated structural members were sent out to be heat treated per our repair from Textron.
We had inspectors conduct non-destructive inspections. Those inspections located a few more cracks that needed repair.
One of the engines hit hard enough to bend and crack the case in several places, so we were pretty sure that engine was beyond-economic-repair (BER). Pratt and Whitney did all the evaluations on the engines and, although both of the engines were very low time, both were ultimately beyond economic repair.
The owners had a big soft spot for the airplane. (What King Air owner doesn’t?) They wanted to keep it, but they were looking at the cost of it. The cost of repairing the airplane with the engines that were already on it would have been well more than the airplane’s worth.
We talked to them about Blackhawk Aerospace (for which we are a distributor), and we were able to secure two PT6A-135 engines for a price comparable to having one engine repaired. Blackhawk was fantastic. They worked with us on the cost of the new engines, and they were willing to accept the old engines back as cores.
This took a few weeks, but we had plenty to do in the meantime.
The engine mounts were actually twisted, and we sent them out to an aviation welding shop that does engine mounts, and they were able to evaluate, repair, and do NDI/NDT testing.
We replaced and upgraded the engines to Blackhawk PT6A-135.
Once the belly was repaired, and the flight controls were repaired, we were able to put the new engines on and start the whole engine rigging process. (Rigging the engines means that when the throttles are pushed forward in the cockpit, the engines do what they’re supposed to do.)
There are stringent parameters on how engines run. If they’re not rigged properly, it’s really easy to damage them, and this can get very expensive.
The Landing Gear
Part of the problem was that the pilot realized a little too late that he hadn’t put the landing gear down. The aircraft landed on the landing gear as they were trying to extend, and it made the damage worse.
We removed the landing gear and inspected it. Several different parts of the landing gear system had been damaged because of the landing. We sent some parts out to be overhauled, and some of the components were either repaired or replaced.
Upon further inspection, we found that the landing gear actuator rods had punctured the back of the engine nacelle area. We also found that in the two engine bays, there were holes poked into the fuel cell area. The bladders, fortunately, had not ruptured. We repaired those and repaired a hole in the nose gear bay caused by the actuator.
The entire landing gear system was rerigged because it was affected by the incident.
We completed all the landing gear checks to make sure they retracted and were rigged appropriately and checked the emergency landing gear operation.
Damaged Propellers from the King Air 90 Rebuild Project
The propellers were totally destroyed.
We spoke to our contacts at Raisbeck Engineering and upgraded from the existing Raisbeck power props to swept tip, turbofan, four-blade propellers. Because of our relationship with Raisbeck, we were able to get an excellent deal on the propellers.
Other Damaged Areas
There were a lot of little extra things that we had to do to complete the project.
The inboard flaps were too damaged to repair, so we replaced them with repaired/reskinned units.
The outboard flaps were repairable, so we repaired them.
The ailerons were okay, but all the rigging had to be redone because it affected every control service on the airplane.
We replaced the flap motor and the flap gearbox because they were damaged in the incident.
We inspected and lubed all of the flap actuators and changed one flap actuator.
The landing gear mounts needed repairs.
The nose gear mount needed repair because the nose gear had punctured the top of the nose gear bay.
We replaced all the flammable fluid hoses (that’s a ten-year inspection item).
We did the structural inspections on the fuselage flooring.
So we did quite a bit.
We picked up the airplane in July but didn’t get approval to start working until mid-September. All in all, it took nine months.
We ordered big parts, little parts, and all of the standard phase inspection parts.
Once the new engines were installed and everything was repaired, it was just a matter of doing all the flight control checks and the operational checks. That process was very extensive. We basically had to do just about every check in the maintenance manual because we had touched just about every system on the airplane.
The customer wanted to do a lot of extra work so he could get the airplane back and not have to be in maintenance for a while. We complied with the Phase 1 – 4 inspections as part of all the repair package. We got the aircraft to a point where he won’t have scheduled maintenance for the next two years.
It was a job well done. We got the aircraft back together to where there is still some equity in the airplane. There have been no issues, and the owner is pleased.
A Shout Out for Our Partners
Aerospace Welding – engine cradle inspection for our engine mounts.
Blackhawk Aerospace – the engines
Davis Aviation – inboard flaps
Nextant Aerospace – NDI for our wing bolts, for the engine mount, attachment points, etc.
Pratt and Whitney evaluated the damaged engines.
Raisbeck Engineering – the props
Trace Aviation – the landing gear and flaps
Textron and their engineering team provided a repair scheme for the main fuselage repair. We worked hand in hand with them shoring up the airplane to make sure it didn’t twist when we had everything apart.