The Beech 95-C55 experienced a gear-up landing at the airport in Delta, Colorado, after the pilot was unable to extend the landing gear.
Post-accident examination of the landing gear motor revealed that the sector gear teeth were partially sheared and were bound with the worm gear teeth, resulting in interference.
Once the gear was turned past the sheared area, the assembly functioned with no anomalies.
Review of maintenance logs revealed that the most recent annual inspection, which included the landing gear system, was completed about six months before the accident with no anomalies noted.
Probable cause: The failure of the landing gear to extend during landing approach due to the interference between the landing gear motor’s sector and worm gears.
NTSB Identification: CEN17LA091
This January 2017 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
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This part failure will be more common with our aging aircraft fleet. This was a 1966 model, and old aircraft will need to have all of their moving parts closely inspected.
I fly a 1961 Cessna 175B and we have found a number of 58 year old parts failing, and needing replacing.
The main gear drive actuator should be disassembled for inspection and at least, renew the lube.
The most common magneto failure is the distributor gear having teeth shear off causing misfiring or complete failure to provide spark to the plugs.
I hate these types of incidents. When equipment fails for no good reason, without a probable reason for the failure, we don’t have anything we can do to prevent or circumvent the failure.
As it happens, I’m involved in such an incident (was a partner in this Piper Lance) where a Piper Lance was totaled because both mags failed, simultaneously, while on approach to an airport over a “densely populated” area — as in, no good place to set it down without putting those on the ground in harms way. It had been about 90 operating hrs since overhaul. NTSB and another group have examined that Mag set up and no one can figure out why they just stopped producing spark.
Back to this gear problem: What are we to learn from such a situation? What are we to do differently?
Overall, how do we solve this type of problem in the GA world?