Accident Study: Landing Gear Failure

My local flight school had an unexpected incident recently involving a failure of the nosewheel. The plane was a Piper Arrow, which has a landing gear system that fails to the down and locked position. This means that if you lose hydraulic pressure, the gear will fall down and lock in position. It has an emergency extension system and even an automatic extension system if you forget.

The Piper Arrow is part of the Cherokee line of Piper aircraft. Over 32,000 of these popular planes have been built since 1961. The arrow itself is a very common plane and you might expect all of the problems to be ironed out. But this is aviation, and anything can happen, which is why we train so hard for what might happen.

In this case, the aircraft departed on a training flight with a very experienced student and a very experienced instructor. I know both of these people personally and have flown with them. They are some of the most qualified people anywhere to handle an emergency like this.

The gear won’t lock

The flight called for some stall practice, which involves flight in landing configuration, so the gear was lowered and raised several times.

However, the final time that the gear was raised there was a problem, although the pilots didn’t know it yet.

Upon returning to the traffic pattern the landing gear lever was lowered and the two main gear lights illuminated. The nose gear light did not illuminate! So they departed the pattern and tried raising and lowering the gear to no avail. They contacted the flight school and flew past so others could take a look.

The nosewheel was down, but not quite all the way, and it was off to the side a bit.

Luckily they had a good amount of fuel so there was time to think about how to handle this situation. The biggest question is about whether to land with the main wheels down or up.

A main wheels down landing would damage the nose of the aircraft if the gear collapsed, and the prospect of sliding in nose first was not very appealing.

However, landing with the gear up guaranteed damage to the plane and danger to the pilots even if the nosewheel was planning on staying extended. In addition, if the nosewheel did stay extended the landing would be very rough as the aircraft would necessarily roll to one side of the nosewheel.

They chose to land with the main wheels extended and locked.

Landing without a nosewheel

The landing was beautifully executed! The instructor touched down gently on the mains and kept the nose off the ground as the aircraft slowed. They pulled the mixture out so the engine would shut down just as the prop touched the ground.

The nosewheel slid partially up into the wheel well and the prop touched down with a loud metallic scraping noise. The plane settled onto the nose and slid down the runway. It appears that the brakes were not applied and the plane slowed down to a stop after a few hundred feet.

 

Some other instructors ran to the plane as the firetrucks rolled up behind them. There was no fire, and the damage to the plane was surprisingly minimal. The propeller is bent and the whole engine will need to be inspected and likely replaced, along with the motor mounts. The removable cowling is toast and the nose gear systems need to be rebuilt, but that is a very gentle outcome for the type of failure experienced.

What went wrong

This whole problem was caused by a small piece of metal that guides the nosewheel to a centered position as the gear is retracted. This guide ensures that if the wheel is down but turned slightly, it will be lined up to fit in the wheel well.

When the gear was raised after the last stall practice, the guide bent on one side and the roller that normally travels down the middle of the guide fell off to that side. Worse still, the bend in the guide rail was very sharp and it acted as a hook, grabbing the roller as the gear was extended! In the image below I am holding the bent guide. See the left side, which is how it is supposed to look, and the right side which has bent down into a hook!

IMPORTANT: Please read my disclaimer below about accident studies


This study and all accident studies are not meant to judge anyone, their actions, or their skills as a pilot. I do not claim to know what the pilot did or what he/she was thinking. The purpose of these accident studies is to better understand what causes accidents and how to avoid them. Comments and other points of view are always welcome as long as they are respectful towards everyone involved.

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