Courtney #87: Incorrect Bolt Causes Quicksilver Fatal Accident - Light Sport Airplane - Ultralight

Great video. Such a tragic waste of life. Would the corrosion be visible enough to be seen during pre-flight inspection?

Hi Courtney, wow you blew me away, when you said the plane had been used in/near salt water , I thought to myself a stainless steal bolt would be the way to go for sure ! glad I was proved wrong,
Are class 5 bolts high tensile ?? Cheers

Courtney, When I got my used MX I received the manual as well. I went bolt for bolt all over the plane and found several that were common hardware store bolts. Over the next couple months I became very intimate with Bever Bourne at AirTech and got every single bolt (and other parts) corrected to the manual specs. You wouldn't believe how many incorrect and underrated bolts I found on the plane. After correcting everything the plane flew perfectly. I shudder to think what might have happened if I had flown with all the rusted and corroded common bolts and nuts I found on that plane. This video may save someone's life. It's no joke to be a thousand feet in the air with unsafe hardware. Thanks for the video. You're valuable to the ultralight community. Keep up the great work.

Thanks for posting this. As Dan Wroe said in your FB publication, we lost two good friends from that accident involving Capital Area Light Flyers club members. As I result, I took my wings apart and replaced all of the bolts with new ones. Some of the old ones were getting rusty. One was an incorrect bolt.
I'm now doing the same on the wings of a second MXL II. One of the bolts was so rusted that it snapped while I was trying to remove it. It was not an. A&N bolt.

Great video Courtney

Thanks Courtney good advice ! Your looking hot too 👍

Thanks Courtney, We all need to maintain our Quicksilvers and the correct hardware is important. I have pulled grade 8 bolts from those compression strut / wing wire attachments on the spars on plains I have worked on. Grade 8 may have a higher ultimate strength but are much more brittle than the proper grade 5 or AN bolts. The aluminum plug in the end of the compression tube is a 1/4-20 thread and does not use a AN bolt. The leading edge outboard wing wire is the most important of these wires and it's vertical bolt should be a AN as you say here! It should be installed from top to bottom so you can see the threads showing below the nylock nut when you preflight.
Most Quicksilvers are single seat being flown as part 103 ultralights with amateur maintenance, often without a copy of the manual to refer to. We all need to protect the reputation of the planes and keep our self safe with proper maintenance.
Quicksilvers are quite safe but these preventable accidents from poor maintenance or ignorance are really sad.

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As a former aviation quality assurance inspector and airframe mechanic (mostly military) I am appalled by the widespread use of non aeronautical hardware in ultralight and light sport aircraft. I have been researching ultralight aircraft in earnest with intent to buy in the near future (leaning quicksilver). I am especially disturbed by the use of soft aluminum “pop rivets” in the construction of airframe components and the integration of metric hardware between engines and airframes. Even though AN hardware is cadmium plated it can only resist corrosion. Special attention should be paid to areas where dissimilar metals are in contact such as bolted aluminum tubes. This is known as galvanic corrosion and is especially troublesome in electrolyte rich environments such as humid salt air. Typically aluminum which is anodic tends to suffer the most damage. I can only hypothesize that the bolt in question was some cheap ungraded hardware.

Stress corrosion cracking can affect any kind of material, no? Is there any definitive evidence that this failure would have not occurred with the factory recommended bolt installed?

Sad and tragic story. It's good to see you sharing this valuable information.

I would take the ntsbs words with a grain of salt. stainless steel bolts don't suffer from corrosion, in fact an bolts will rust much faster after the protective cadmium layer has worn off. If there is such little safety factor that going from a an bolt to a stainless bolt would sacrifice the structural integrity, I would think the wrong size bolt was used from the get go.

After your first post on FB about this I took a look at my wing bolts. I was surprised that 2 were not AN grade bolts!!.. I thought “OH NO..someone has hacked my plane!……. So, I went to the manual and there is was!!!!. Grade 5 bolts instead! You learn something new every day. And …I really appreciate the time and information you bring to us fellow flyers..

Crazy to think a single bolt failure led to a wing collapse.

Great video Courtney. Please keep up the good work.