By Kent Ewing, Vice President, BPT INC
A few months ago, my friend Todd Ericson, President of Society of Experimental Test Pilots called and asked if BPT (Bonanza/Baron Pilot Training) could provide some hands on training of the eight pilots who were flying the Virgin Galactic Baron…a BE58TC. Of course the answer was YES and after a few months of scheduling conflicts, we went just two weeks ago to Mojave. Todd confided in me that they were burning out cylinders and one of the turbos just in the past few months and they requested training pointed at engine management in particular.
Bill Hale, who is the absolute guru of Baron Systems and of course myself the masterful instructor of flying the Baron series on one engine went to Mojave the end of March just prior to our annual Fresno BPT clinic.
We arrived early Monday morning in order to get set up with the power point on their IT systems. To our amazement the parking lot was full and overflowing at 0700…first sign of a thriving business with an amazing “get it done” culture.
After a morning of ground school with eight test pilots, three of who were astronauts, we wowed them with our vast knowledge of their multi engine trainer, only to discover that they were changing the landing gear motor. They use the Baron to remain current in multi engine procedures, which cross over to the White Knight, the aircraft that carries the passenger rocket to plus 40,000 feet for release for the second stage to 60 miles. However, as the program progresses, V.G. uses the Baron for logistics flights to/from Long Beach and to/from Las Cruces, NM. Just the day before, the pilot had to crank the gear down at Long Beach, and had flown the aircraft back to Mojave with the gear down. Chris, the VG mechanic was positive that upon receipt of the parts needed, that we could definitely start training flights on Wednesday. Well, how lucky for Bill and myself to have an off day to tour the hangar, the White Knight aircraft, watch a rocket test firing, and fly the simulator!
Finally on Wednesday we had a full schedule for Bill and myself to fly about one and a half hours with each Virgin Galactic test pilot. Bill flew a full syllabus flight with Todd Ericson, which included emergency extension of the landing gear…thereby testing the gear relay, the endplay of the sector gear, the new gear motor and the dynamic brake tolerances. The landing gear system checked out perfect in all respects.
Next flight was Kent and CJ Sturckow, a career Marine F18 pilot with 4 shuttle missions in his logbook. He practiced steep turns, spiral demo, and clean stalls before we extended the landing gear for the first landing configuration stall. The new gear motor ran for about half the normal time, stopped and the gear motor circuit breaker popped. Since there was no loud noise indicating a possible rod end failure, I had CJ try to finish the gear extension with the hand crank. He was only able to get about 6 more turns! I also tried the hand crank to no avail. I even climbed in the back to get a better purchase on the hand crank…no luck.
Stowed the crank, pushed in the C/B and raised the gear normally. One more extension electrically gave the same result as before…we knew the gear was hanging about half way extended…. I could see the nose gear in the shiny paint on the nacelle was about 45-degree angle. We now got Bill Hale and maintenance on the common radio. Bill got Dave Monti (our BPT maintenance expert) on the phone. We then all agreed it might be possible to get them further down by pulling some G’s.I got strapped back in the front and CJ conducted a marvelous pull up, zero G push over, to about a 3 G pull up.
Nothing. Dave said that usually works to get a nose gear out that has a broken actuator rod end. Ok…. brought them up electrically, max conserve, and established an overhead pattern while V.G. chief pilot manned up the Extra 300 with Chris Johnson, the maintenance expert in the back seat.
At this point I was quite sure we were going to be on the six o’clock news with a controlled gear up landing!! But wait a minute…. there was one process we had not tried. To this point we had not cranked the gear down from the full up position. So, thinking it would be difficult, I unstrapped and got into the back again, pulled the C/B, and started cranking. It went extremely easy the first 40 cranks…just as normal as could be…a little harder to the end and at 52 turns I knew they were down. But wait…CJ had no green lights. Oh sure, another gotcha…during the zero G CJ’s shin had turned on the Nav lights which of course dims the landing gear lights. Nav light switch off…. three green followed by confirmation from the crew in the Extra 300…. followed by an uneventful landing.
After a thorough safety debriefing with the V.G. safety team members, the attention now turned to why a new gear motor and a new relay had not resolved the recurring landing gear issues.
Looking at the Illustrated Parts breakdown in figure 1 and 2 below, note item number 25.
This is the worm gear shaft that interfaces with the sector gear. Item 24. The gear motor drives it on the forward end and the manual hand crank on the aft end. When Chris broke down the entire assembly he found a lot of bronze or brass coloration of the gearbox oil and some broken metal at the crank attachment point. See photos and remarks from Chris below. After all the date on the gearbox was 1977!
So the conclusion is that when driven by the high rotation electric gear motor (especially a brand new one) the shaft shifted enough to jam against the sector gear and mechanically stopped at around half way gear down. This explains why we were unable to crank the gear the rest of the way down using the hand crank. Then when we cranked the gear down from the full up position we were not putting the same high revolution loads on the worm shaft and we were able to crank the full 50+ turns to achieve manual gear extension.
Nothing like a bit of luck to make your day!
Good morning Kent,
The story as it happened is very well documented aside from a few small discrepancies in the last paragraph. All parts including the woodruff key were. No parts were found missing during my tear down inspection.
Issue 1. Gear couldn’t be lowered manually.
We have positively identified the reason the hand crank would not budge. After removing the hand crank assembly from the gear actuator case itself, the hand crankshaft was jammed solid completely removed from the gear actuator. Upon disassembly of the hand crank mechanism I discovered a piece of steel material undoubtedly from the manual extension end of the worm gear shaft that had wedged itself between the manual extension shaft item 6 and case item 7. Pictures below showing just that.
Above is the evidence I found of the metal piece gouging the manual extension case item 7.
Above shows the small piece of steel and the metal filings that were found during disassembly of the hand crank assembly.
Above is item 6 the manual hand crankshaft and the evidence of the wear between the case and the shaft.
Above is the manual extension end of the worm gear shaft with visible damage chipping.
Issue 2. Why the circuit breaker tripped half way through the cycle?
I believe it to be as simple as new motor in combination with an old weak breaker and an old very loose gearbox.Upon further disassembly of the gearbox I discovered quite a lot of material suspended in the gear oil.
The damage to the sector gear wasn’t easily seen without a magnifying glass and even more difficult to get good pictures of. I also didn’t measure the exact amount of end-play but there was slight movement of the worm gear shaft fore and aft in the housing. After removing the shaft from the housing the main bearing from the manual extension end of the shaft had play and makes a chattering sound when spun by hand.
Christopher A. Johnson