08-21-2014, 06:43 PM
I'll assume your 500 hr check as gospel, because I don't really know the inspection intervals. Also there could be different phase of checks during a longer period of time. For airplanes, there are checks that are more frequent in some areas because they maybe high stressed and high fatigue locations based on the airframe analysis.
Fatigue is critical in airplanes as well. It is the cause of just about all structural failures in the industry. However the harmonics and vibration of choppers makes them susceptible to fatigue and they are basically built a lot more "rinky dink" than airplane.
Fatigue can be very hard to predict because you need to have accurate load data or load cycles for the aircraft, accurate stress analysis, and accurate calculation of stress intensity factors at fillets and joints. These 3 groups of data need to be accurate in order to accurately predict fatigue. If there is doubt in the accuracy of any of these groups, conservative assumptions are made.
Then you test and see how good the analysis was.
The F-35 fatigue test article cracked a bulkhead in half the time it was supposed too. It was the bulkhead that carried the most loads between the wings also.
A lot of times these tests open up areas of concern that may not have been seen during the analysis phase. Sometimes the analysis shows to be conservative in other areas. It's all why testing is necessary.
Good job in instigating me to hi-jack the thread, TD.
Sorry Cory
Fatigue is critical in airplanes as well. It is the cause of just about all structural failures in the industry. However the harmonics and vibration of choppers makes them susceptible to fatigue and they are basically built a lot more "rinky dink" than airplane.
Fatigue can be very hard to predict because you need to have accurate load data or load cycles for the aircraft, accurate stress analysis, and accurate calculation of stress intensity factors at fillets and joints. These 3 groups of data need to be accurate in order to accurately predict fatigue. If there is doubt in the accuracy of any of these groups, conservative assumptions are made.
Then you test and see how good the analysis was.
The F-35 fatigue test article cracked a bulkhead in half the time it was supposed too. It was the bulkhead that carried the most loads between the wings also.
A lot of times these tests open up areas of concern that may not have been seen during the analysis phase. Sometimes the analysis shows to be conservative in other areas. It's all why testing is necessary.
Good job in instigating me to hi-jack the thread, TD.
Sorry Cory