After a cross-country flight and during the landing roll at the airport in McKinney, Texas, the Cessna 340’s left main landing gear collapsed, causing substantial damage to the aileron.
An examination of the landing gear found the bell crank pivot bolt and gear down-lock broken.
A review of the airplane’s maintenance manual revealed that the landing gear system is to be disassembled/inspected every 10 years/5,000 landings, after an initial inspection after 20 years or 10,000 landings.
Additionally, the maintenance manual indicates that the main landing gear bell crank pivot bolt is to be inspected for wear every three years (or 500 landings), after an initial inspection at three years or 1,000 landings.
A review of the airplane maintenance records did not reveal an entry where the landing gear inspections had been accomplished. The records revealed the airframe had accumulated 5,799.3 hours at the time of the last annual inspection, which was dated September 1, 2016.
It’s likely that the landing gear pivot bolt developed a crack over time, which then failed during landing, causing the gear to collapse.
Probable cause: The failure of the bell crank pivot bolt, which resulted in the left main landing gear collapse. Contributing to the accident was the lack of landing gear inspections in accordance with the airplane manufacturer’s maintenance manuals.
NTSB Identification: CEN17LA351
This September 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.
“Weigh the gear”…..checking the downlock and uplock over center breakaway value in pounds. All the 300 and 400 series Cessnas we had in the ’70’s had the same MLG type. Procedure is in the maintenance manual.
In the ’70’s with our C310 and C402 fleet, the cabin floor came up and the gearbox and linkages were inspected and lubed, and the gear was “weighed” per the manual, and adjusted only if the results were out of spec. The gear was weighed at every 100 hrs., too.
What does it mean to weigh the gear? Not familiar with that (I fly a 340 but I am not an A&P).
It would be a simple mod to add a digital counter to count the gear retractions, using the up-lock switches as inputs, similar to adding a Hobbs meter.
The mechanics most familiar with these planes suggest re-rigging the landing gear every year, or at least every other, regardless of landings.
Good maintenance shops (and our type club) recommend rigging the gear at every annual. The gear is unusually the most common source of accidents in these airplanes and it’s almost always due to a lack of proper maintenance.
Also, given how long ago this accident was, why is this being republished now? Just curious.
We don’t publish accidents until two years later, because it takes the NTSB about that long to determine probable cause in many of them.
For aircraft with these types of inspection guidelines in the POH, shouldn’t a documentation procedure be developed to record the landings?
A number of landings could be deduced from a pilot’s log, but an aircraft could be operated by a myriad of pilots….whomever they may have been. Landings aren’t required to be recorded in an aircraft log…..only maintenance performed, with dates and times in service. I can only assume that a number of landings would be a best-guess number…..at best.
I have to ask this question: where does one record the number of landings?
I record landings that I need for showing currency. But I don’t know of a place to collect all the landings in an airplane’s logbooks.
So only the checks based on hours seem to be the ones that would get followed. ( And these apparently weren’t).