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I was also impressed by their described statistical analysis. Some may recall that I did some ad-hoc analysis of this issue a few months back, but based on their reply I am satisfied that Piper worked with the right experts to perform a high-quality analysis of failure rates. That the FAA...

What percentage of hard landings do you think get reported?

I don't want to speculate too much since I'm a statistician and not an engineer, but if I had to guess I'd say hard landings.

Some would debate that: https://www.pilotsofamerica.com/community/threads/pa28-32-wing-spar-ad-show-me-the-data.147900

Ever had a cracked wing rib or failed an eddy-current inspection?

Imagine you have infinite-load tie-downs. A strong storm hits and the load (which I think we've concluded the aircraft has no coherent rating for) damages the airframe invisibly. You now have a damaged plane but don't know it. In contrast, the person with the 1000lb tie downs had them snap and...

Sounds like no such "obvious" opportunities exist. It's almost as if any knowledge you may have about the market is already priced in...

Yup. What are the tie down eyelets rated for? I doubt they’re rated to hold the entirety of the max aircraft flight load.

I use lashing straps: https://www.harborfreight.com/set-of-2-1-inch-x-12-ft-lashing-straps-67386.html They may not hold in a hurricane, but they're dead simple to attach. You can tie them off if you want a more solid hold.

I ammended my above comment after you quoted it, but this is not the case. Batteries can be measured at different discharge rates. Lead acid batteries are well-known to have lower Ah capacities at higher discharge rates. In the less-regulated marine space, it seems very likely that manufacturers...

Maybe Ah in boat batteries are measured differently (e.g., at slower than C1 rate), or boat electronics don't tolerate any voltage dip. I don't see this necessarily directly translating to aviation, where batteries are tested to comparable cutoff voltages at C1 and electronics generally tolerate...

I don't buy this explanation. People aren't (only) worried about killing their batteries; they're wanting to be sure they have enough Amp-hours to get out of the soup when the alternator quits. Concorde measures their capacities to an end-point voltage of 10V, a level at which the battery may be...

The bane of statistics! As noted it's impossible to determine statistical power without some alternative hypothesis, but generally the sample sizes used here ought to be sufficient that we'd identify a trend of the failure mode varied substantially. Caveat: if there is fatigue cracking but it...

Absolutely. The data are certainly in support of inspections. What they do not support is (a) an initial period before inspection longer than the inter-inspection period, or (b) a life limit.

CALCULUS ALERT: The failures are cumulative in that each hour could cause cracking that fails the inspection later. The cracking (under the model) occurs with equal probability in any hour regardless of age. In this way the ECI failure probability increases, but the rate of increase decreases...

:yeahthat:

Imagine that every hour you fly you roll a 500,000-sided die, and if it lands on 1 the spar fails. Would you (a) check the plane at some interval to see if you rolled one recently, or (b) quit flying after 12,000 rolls?

The 450B is fantastic. I recently had mine re-wired for stereo and the aural separation makes it much easier to handle handle two comms (e.g., picking up ATIS while still listening for calls from Approach). The music distribution is fantastic. I like that I can set different mute modes for each...

Unfortunately this isn't a question the data can necessarily answer. We can say that many more spars failed ECI than fell off.

Interesting point. Are you able to see evidence of duplicate report lines in the tables from reports that you're familiar with?