Structural Failure

[EdFred]

And he typically sits in the right seat.

Yes, because standing in the right seat makes it quite difficult to fly.

 

[SkyDog58]

Shear or not it appears per Rons post above that nut is still needed. Plus there has never been a failure of a Jesus nut that I’ve heard of but do know of a few bolt failures caused by the lack of a nut. So I guess it depends on your viewpoint.

But as a bit of trivia, the Jesus nut terminology actually started as the Jesus bolt back in the days of the WWII PBY Catalina. Seems there are only 2 bolts that held the Catalina wing assembly to the fuselage and someone coined the Jesus Bolt term. Fast forward to the early 60s and the formation of the 11th Air Assault to prove the “new” air mobility doctrine. As legend has it, a number of previous PBY pilots switched to helicopters and once it was noticed there was one nut holding the M/R hub on, they resurrected the Jesus bolt slang but changed it to Jesus nut. So I guess historically, its really all you plank-wing guys that have been flying around with Jesus bolts all this time. As the rotor turns….

View attachment 105210
https://www.smithsonianmag.com/air-space-magazine/legends-of-an-ocean-crossing-seaplane-180971743/

Never understood the term jesus nut. Supposedly it is because that is what you’ll yell if it fails. Me, I’m more likely to yell f**k, so to me they are f**k nuts.

 

[SkyChaser]

Never understood the term jesus nut. Supposedly it is because that is what you’ll yell if it fails. Me, I’m more likely to yell f**k, so to me they are f**k nuts.

See, I thought that they were called "Jesus nuts" because they're the only thing saving you from a imminent demise.

 

[Jim K]

I was told it's because if it fails, you're going to meet Jesus.
Or Old Scratch maybe.
Perhaps "St. Peter bolt" would be more appropriate.

 

[EdFred]

I was told it's because if it fails, you're going to meet Jesus.
Or Old Scratch maybe.
Perhaps "St. Peter bolt" would be more appropriate.

I've heard the handles in cars called Jesus handles, along with a few other Jesus [things]. Always figured it had to do with praying. Or maybe in the case of my friend, his only exclamation is, "Jesus!" The intensity and volume of it determines the type of reaction whether it be amazement, anger, or fear.

 

[Larry in TN]

Read about load factors, airspeed, and the Vg diagram. It's in the Pilot's Handbook of Aeronautical Knowledge on page 5-38.

 

[Tantalum]

There have been quite a few, but like almost all planes, occurred when the design limits of the aircraft were exceeded.

Here is one. One thing to note is how low the Va is on these aircraft. Doesn't take much to get them out of the envelope if you lose control. Note to self. Don't lose control. Reality is that when most pilots lose control, the outcome is the same whether the plane hits the ground in one place or several places.

http://www.aero-news.net/index.cfm?do=main.textpost&id=3d02cc76-ceec-4a87-9eef-1edd7fc472aa

Damn, well I guess anything can break if you push it hard enough

 

[Bell206]

Supposedly it is because that is what you’ll yell if it fails.

Sort of. The consensus is not so much what you yell, but that Jesus is the only person who could help you when that nut or bolt fails. Given there has been no Jesus nut failures, its kind of hard to prove it. Then again as noted above there have been "Jesus bolt" failures but it seems those pilots were not in good standing to get any assistance from above. I always figured if there was some sort of divine intervention it would be along the same line as shown in the Amazing Stories episode, The Mission. Not about a nut or bolt, but it goes along the same premise.
https://kiefersutherland.net/amazing-stories-the-mission/?v=79cba1185463

 

[Dan Thomas]

See, I thought that they were called "Jesus nuts" because they're the only thing saving you from a imminent demise.

The correct term is "mast nut." There was an accident here in Canada when a helicopter took off without that nut. The massive torque on the splines of the mast and rotor head kept the head on until descent, when torque is reduced. http://www.tsb-bst.gc.ca/eng/rapports-reports/aviation/2000/a00q0046/a00q0046.html

We used to keep rolls of bright red surveyor's tape to mark disassembled stuff so nobody would fly the airplane if something was apart but not obvious.

Here's another fascinating story of what can happen if a simple, tiny cotter pin is left out: https://www.avweb.com/flight-safety/saved-by-a-leatherman-tool/

 

[Snowmass]

The wing on your 182 won’t fall off, the fuselage will.

Seriously though, there is a structural inspection now required by AD for the lower strut mount.

That AD points out the arrogance and/or stupidity of an FAA engineer by putting a calendar limit on the AD as well as a flight time limit for inspection. Fatigue failures are flight time/turbulence dependent, period. And, on top that, we have pay that guy's wages.

 

[Maxnr]

Be glad your are not in a helicopter. Just think, there is just this ONE big nut up there.

Had a structural failure once in a helo on a pretty saturday morning. A Bell 212 with 38K hrs on it. I was executing the Helo arrival and up with the twr. Suddenly I had to input almost full right stick to maintain level flight. No option to land as I was over a cypress swamp. Lots of trees in the water. Made it to parking in a six inch hover. Had to ride along as it was towed into the hangar. Fuselage was somewhat warped and doors were jammed. Mx had to free me. It was a mess and drew a crowd. I kept the bragging down to a respectable level. "Yeh. I flew that in."

 

[camorton]

I'll admit the thought crosses my mind also when I hit some really rough air in my 182. Then I consider the 80 million flight hours collectively accumulated on the 182 fleet to date, and I'M gonna be the first one to snap off a wing? That's some ego right there! Human nature really makes me laugh sometimes.

C.

 

[Bell206]

Had a structural failure once in a helo on a pretty saturday morning. A Bell 212 with 38K hrs on it.

Xsmn pylon or lift link failure?

 

[danhagan]

.... One unpleasant thought I commonly run into is "gee that would really suck if the wing snapped off right now". This thought ruins the magic of flight for me a little bit. If the engine quits you have a chance, but if the airframe fails it's over right?

Here's my question. How hard is it to fail the airframe on a 182 from the 80's? I had it inspected for corrosion in the pre-buy and it recently just passed annual, but I'd like to squash this thought from my head so I can enjoy flying a little more.

I think it's ready to go at any moment ... just LOOKING at it could cause failure. I'm POSITIVE the cross-over spar was neglected in the pre-buy and annual as it's a pain for the mechanic to get to ... recommend you get out from under it immediately ... being they great person I am, I'll take it off your hands for $50 and save you all the future worry and aggravation

 

[Skyrys62]

Jesus took the wheel

 

[Maxnr]

Xsmn pylon or lift link failure?

Floor on L. side separated and dropped 4"to 6". Most separation was at the pylon. That L. well area had the optional 200 pound aux fuel cell that took up the whole "hell hole." Ship was down for a month. BTW she has a Canadian reg last I heard and still doing sightseeing flts. She began life as a factory prototype.

 

[Getonit]

I more worry about the tail breaking off rather than the wing.

 

[Dan Thomas]

That AD points out the arrogance and/or stupidity of an FAA engineer by putting a calendar limit on the AD as well as a flight time limit for inspection. Fatigue failures are flight time/turbulence dependent, period. And, on top that, we have pay that guy's wages.

Did you read the AD? It refers to a service kit recommended by Service Bulletin in 1995, to strengthen that area. The AD was issued in 2020, 25 years later. Cracks were still showing up, whether on the kitted or unkitted airplanes they don't say, but all airplanes must be inspected. The AD's preamble says this:



More than four dozen airplanes reported with cracks. How many are out there that get the $295 annuals that have unnoticed cracking?

Real mechanics know about Service Difficulty Reporting, where stuff like cracks or corrosion or other serious defects encountered during maintenance are reported to the SDR system. That information is used to determine whether an AD is warranted. Obviously, more cracks were reported, so the AD was issued to force the kit installation or the replacement of cracked components.

Would you rather the FAA and Cessna waited to take action after the wings came off a few 182s?

 

[Bell206]

Floor on L. side separated and dropped 4"to 6". Most separation was at the pylon.

Even worse. Sounds like floor beam cap failure. Must have been a fun ride. Lucky the servo mount stayed put.

 

[Maxnr]

Even worse. Sounds like floor beam cap failure. Must have been a fun ride. Lucky the servo mount stayed put.

Quite a nice ride. Seemed like it just got Left wing heavy like right now. Worst part was " What just happened ?" I put my observations on the ICS and it went straight to the CVR. For posterity. TWR couldn't help me and only added paperwork. The 4 to 6 inch separation was when sitting on the ground on the gear. Was told that it was more separated in flight. Glad I was solo and light on gas. It just gently let go about 5 miles from KHUM over the swamp. let down from 500' pattern alt to 250' and slowed to 75 - 80 kts. Many unknowns, but for some reason I thought I could survive a 250' fall. Silly me.

I don't think the aux fuel cell had much to do with the failure even tho its weight is directly on the floor. The weight of the left side two seats (if installed) is mostly taken on the vertical bulkhead. I think that some of the previous cargo runs may have had some bearing. We were using a fork lift to load oil field things called DSA (Drill "somthing or other") Adapters. Solid steel, bagel shaped, a foot or more thick and varied four to six feet diameter. The lightest one that I carried was 750 lb, the heaviest was 1,500 lb. Maybe not enough 2 X 4's under the load. As usual, each minute delay cost the rig big money.

The next one I had was a SK76 Tail rotor pylon spar totally cracked full length. An inspection that was due was "pencil whipped". I survived fat, dumb and happy and the damage was caught on the phase insp next day.

 

[Wagondriver]

I told an instructor friend of mine that I really don't feel comfortable at many thousands of feet above the ground, especially in my kit plane. He told me that that made no sense, altitude is your friend. I replied that at low altitude, I won't have as much time to think about it.

I put it in the back of my mind, unfortunately when getting thrashed in turbulence, it shakes it more to the front of my brain!

 

[Bell206]

I don't think the aux fuel cell had much to do with the failure even tho its weight is directly on the floor.

Probably not on the fuel cell. Those beams cap issues have been a "feature" on that airframe since the UH-1H days especially at STA 129 which is just forward of pylon. Every primary load ties into those beam/cap angles: lift beam, pylon walls, floor, etc. As I recall there were various cap failure modes from improper loading as you noted, to external load work, corrosion, etc. Plus you had to be dedicated to check those areas with aux tanks installed and primer only hellholes/internals.

 

[ARFlyer]

I purchased a 182RG several months ago and often take 5-7 hour cross-country trips. Once I get everything set up in cruise, autopilot on, etc my mind will wander. One unpleasant thought I commonly run into is "gee that would really suck if the wing snapped off right now". This thought ruins the magic of flight for me a little bit. If the engine quits you have a chance, but if the airframe fails it's over right?

Here's my question. How hard is it to fail the airframe on a 182 from the 80's? I had it inspected for corrosion in the pre-buy and it recently just passed annual, but I'd like to squash this thought from my head so I can enjoy flying a little more.

They’re stout! Part of my day job is investigating aircraft accidents. I can say without a doubt a properly maintained GA Aircraft will stand up to a LOT more then your standard flight stresses.

I’ve seen a Cirrus stay intact to impact doing close to 400kts. The only inflight break up I’ve been on was due to a Malibu high altitude stall followed by a spiral that tucked under. When that happened the outer portion of the lower wing separated.

 

[SixPapaCharlie]

How do eddy current inspections work? If he wanted some peace of mind could he just request somebody do one of those?

 

[Tarheelpilot]

See, I thought that they were called "Jesus nuts" because they're the only thing saving you from a imminent demise.

It depends on you which one it is. It’s a Jesus nut for me.

 

[eman1200]

…..I know it has held together for 61 years but I can tell it's going to be any day now.

….phew!

 

[Dan Thomas]

I can say without a doubt a properly maintained GA Aircraft will stand up to a LOT more then your standard flight stresses.

That there. My experience as a mechanic has shown me that improperly maintained aircraft can be dangerous. My experience as a pilot also convinces me. A broken crankshaft in flight because it wasn't NDT'd at "overhaul" and had a crack started by a previous propstrike. A badly cracked rear wing spar in an airplane I had towed gliders with and eventually bought to restore after it quit on another pilot. That spar had been cracked when the airplane was blown over onto its back by a windstorm and the weight came on the wingtips, cracking the spar through the strut attach. It had been cracked for over 14 years when I was flying it. Nobody caught it in all those years. That same airplane had an engine failure on me when its carb fell off in flight while I descended from a glider tow. No lockwiring or cotter pins or nothing. Again, cheap inspections. I quit flying it not long after that. When I later became a mechanic I was a lot fussier, and found similar shocking stuff in the airplanes I encountered. And, as I noted in an earlier post here, a 172's horizontal stab forward spar broken all the way through. Found that after I flew it. It had just come out of "annual," too. The wing strut lower bolts were missing their nuts as well. There were other things, over 130 of them, some really serious. We told the owner to bring a trailer and haul it away.

If someone had spun that airplane, the forces on the stab during recovery could easily have failed it.

 

[Dana]

How do eddy current inspections work? If he wanted some peace of mind could he just request somebody do one of those?

Eddy current is black magic. The eddy current equipment I've worked with (not aerospace) displays an abstract "signature" of swirly curves on a screen, meaningless unless you have "good" parts to compare it to and develop the inspection criteria.

 

[Bell206]

How do eddy current inspections work? If he wanted some peace of mind could he just request somebody do one of those?

He would first need to figure out what he wants to look for, otherwise the eddy current checks wouldn't be of much use. In general, eddy current checks need to be calibrated or checked to a standard that replicates the defect you are looking for. You can't simply scan an entire wing and spot a crack. If you read the Piper 1345 spar bulletin will give you an idea what needs to be set up just for bolt hole crack. I have seen wings x-rayed to check internal spars but even those results are not 100% accurate and require additional checks all costing a premium.

 

[wilkersk]

If its been regularly loaded it to max gross weight and taken out and put through 3.8Gs or more, its something to be concerned about.

If, like most Cessna 182RGs, its been usually loaded to something less than max gross, and rarely pulled more than 2gs, I think you're safe. Just avoid flying through thunderstorms, and other very obviously risky things, and I very much doubt the wings will fold on you in the air. If you hit something though, all bets are off.

 

[Daleandee]

You can't simply scan an entire wing and spot a crack. If you read the Piper 1345 spar bulletin will give you an idea what needs to be set up just for bolt hole crack. I have seen wings x-rayed to check internal spars but even those results are not 100% accurate and require additional checks all costing a premium.

You're making the Piper owner's a bit skittish ...

 

[Adam Weiss]

If its been regularly loaded it to max gross weight and taken out and put through 3.8Gs or more, its something to be concerned about.

If, like most Cessna 182RGs, its been usually loaded to something less than max gross, and rarely pulled more than 2gs, I think you're safe. Just avoid flying through thunderstorms, and other very obviously risky things, and I very much doubt the wings will fold on you in the air. If you hit something though, all bets are off.

This is why I always have a little nagging in the back of my mind.
Last summer I was flying out West CAVU and hit the worst turbulence I’ve ever felt. It only lasted a fraction of a second, but I hit my head so hard on the canopy that it drew blood where my headset dug in.
I can’t even guess how many g’s that was, but certainly way more than my RV-9 is rated for.
That got me thinking on almost every flight afterward…what stress did I cause that I can’t see?

 

[Capt. Geoffrey Thorpe]

I can’t even guess how many g’s that was, but certainly way more than my RV-9 is rated for.

Seriously doubt that.

 

[Maxnr]

For some reason, I can't shut up on this topic. Way back in the last century, a fellow pilot in my Nat Guard unit told me of an incident with his day job carrier. A 707 was inbound to JFK over the Atlantic. The auto pilot had a pitch "hard over" at altitude. The crew was able to regain control well, well below 10'000' and pulled a lot of G's. They declared an emergency, unscrambled the cabin and hand flew it in safely. It was widely reported in the papers & TV at the time.

Boeing was called in to help inspect the plane. Only issue found was the wings now had a permanent deformation of more than one foot. The A/C was returned to service. My bud told me crews looked forward to flying this ship because of its improved stability.

 

[Snowmass]

Did you read the AD? It refers to a service kit recommended by Service Bulletin in 1995, to strengthen that area. The AD was issued in 2020, 25 years later. Cracks were still showing up, whether on the kitted or unkitted airplanes they don't say, but all airplanes must be inspected. The AD's preamble says this:

View attachment 105251

More than four dozen airplanes reported with cracks. How many are out there that get the $295 annuals that have unnoticed cracking?

Real mechanics know about Service Difficulty Reporting, where stuff like cracks or corrosion or other serious defects encountered during maintenance are reported to the SDR system. That information is used to determine whether an AD is warranted. Obviously, more cracks were reported, so the AD was issued to force the kit installation or the replacement of cracked components.

Would you rather the FAA and Cessna waited to take action after the wings came off a few 182s?

I do not understand your reply. I personally inspected the the strut attach point when it was just a Service Bulletin. My complaint is using a calendar time in addition to a flight time NOT the idea of inspecting. As an aero engineer I find calendar time to be nonsensical Try again.

Some of you might be interested in a statement made by an FAA engineer at an AOPA convention that older aircraft were designed stronger than newer aircraft since stress analysis was less exact so the engineers over built just in case.

 

[Dan Thomas]

I do not understand your reply. I personally inspected the the strut attach point when it was just a Service Bulletin. My complaint is using a calendar time in addition to a flight time NOT the idea of inspecting. As an aero engineer I find calendar time to be nonsensical Try again.

Calendar times are included for several reasons. Storms can yank at airplanes tied down outside and cause structural stresses. Corrosion is a common problem in that bulkhead where the strut attaches; there are several layers of aluminum there, along with a steel doubler that runs across toward the other side, and steel and aluminum together make a corrosive combination. There have been plenty of low-time, older airplanes junked due to stuff like that. Airplanes rot whether they're flown or not. I have worked on many airplanes and see that. You have one airplane.

 

[Snowmass]

Then if you see corrosion inspect more often. There was not a trace on may 1964 and and tie down yanking stresses are trivial compared to flight stresses.

 

[NordicDave]

Once I get everything set up in cruise, autopilot on, etc my mind will wander. One unpleasant thought I commonly run into is "gee that would really suck if the wing snapped off right now". This thought ruins the magic of flight for me a little bit.

Good reason why a proper annual inspection is required. Corrosion doesn't "just happen".

 

[Bell206]

My complaint is using a calendar time in addition to a flight time NOT the idea of inspecting. As an aero engineer I find calendar time to be nonsensical

FYI: the calendar limit was discussed during the NPRM/SNPRM comment period. However, based on OEM guidance and existing service history it was determined cracks could be also caused by "loading conditions outside of flight, such as ground loads, handling loads, and tie down loads." Did you by chance make a comment during this NPRM period to point out the "nonsensical" ways of the FAA engineers? Out of all 27 comments didn't see any from an experienced aero engineer as yourself.

 

[Therookguy]

I'll admit the thought crosses my mind also when I hit some really rough air in my 182. Then I consider the 80 million flight hours collectively accumulated on the 182 fleet to date, and I'M gonna be the first one to snap off a wing? That's some ego right there! Human nature really makes me laugh sometimes.

C.

So I can take comfort in the fact that I'll join the POA hall of fame if I snap the wing of a 182?