Wanttaja
Sky Savant
I'm giving another talk on homebuilt accident statistics next month, for EAA Homebuilding Week. My subject is engine reliability. Started doing the analysis and came across a curious anomaly.
It's tough establishing how many of a given engine type is installed in the homebuilt fleet as about 15% of the registered homebuilts are listed with a generic engine type (e.g. AMA-EXPR). Out of curiosity, I decided to go down that particular rabbit hole and try to figure out if were any clues as to why.
At first I thought it was a given FSDO. Did a plot by state, but the results were pretty much the same across the US. All states had about 10-15% of their homebuilt registrations listed with AMA-EXPR engines. Sure, many were probably sold and migrated over time, but I'd still kinda expect to still have some concentration if a particular district had a policy.
Then I plotted the data by the year of manufacture, and got this plot:
This is based on the January 2022 FAA registry.
What in the wild world of sports was going on in the early 2000s? Almost a third of the homebuilts in the current registry that show 2005 as their completion date are listed with the generic engine type. Started rising about 2000, tapered off by 2010.
Does anyone have any recollection of any FAA policy changes in this era that might have affected how the engine type was recorded?
Ron Wanttaja
It's tough establishing how many of a given engine type is installed in the homebuilt fleet as about 15% of the registered homebuilts are listed with a generic engine type (e.g. AMA-EXPR). Out of curiosity, I decided to go down that particular rabbit hole and try to figure out if were any clues as to why.
At first I thought it was a given FSDO. Did a plot by state, but the results were pretty much the same across the US. All states had about 10-15% of their homebuilt registrations listed with AMA-EXPR engines. Sure, many were probably sold and migrated over time, but I'd still kinda expect to still have some concentration if a particular district had a policy.
Then I plotted the data by the year of manufacture, and got this plot:
This is based on the January 2022 FAA registry.
What in the wild world of sports was going on in the early 2000s? Almost a third of the homebuilts in the current registry that show 2005 as their completion date are listed with the generic engine type. Started rising about 2000, tapered off by 2010.
Does anyone have any recollection of any FAA policy changes in this era that might have affected how the engine type was recorded?
Ron Wanttaja
