REFLECTOR: For Your Information -- Velocity Gear Fork

[Velocity Aircraft Owners and Builders list]

This topic was posted to the VOBA forum earlier this week with a lot of discussion. It's important enough to re-post on the Reflector for those who may not be VOBA members.

Note: at the end of this message Andy is looking for other owners who may want to buy a stronger nose wheel fork. By ordering them at the same time, we can save a lot of production cost.

Reiff Lorenz, Dayton, OH
Velocity XL-RG, 59% complete
Currently working on: Mounting the electric fuel pump.



Sent: Wednesday, June 18, 2014 1:02 PM
To: Main Forum
Subject: [VOBA Forum] For Your Information -- Velocity Gear Fork

In the interest of sharing information within the Velocity community, I want to make builders and owners of flying Velocities aware of two recent nose gear fork failures experienced by me and by John Youngblood.  We are both back flying with replacements of the current nose gear fork design, but want to apprise the community of the potential development of a new, upgraded nose gear fork.  First, a description of the two nose gear fork failures:

Gear Fork Failure N114MV -- Andy Mllin XL/FG
 [https://voba.clubexpress.com/clubs/495146/forum_message_images/IMG_20130807_195142%5b1%5d_-1941901069.jpg]

[https://voba.clubexpress.com/clubs/495146/forum_message_images/IMG_20130807_203917%5b1%5d_-1943347182.jpg]


August 7th, 2013; shortly after Oshkosh.  A routine flight was completed, the landing was normal;  touch down on the mains, rolled for a bit and let the nose down.  When it touched it didn't feel right.  It was mushy and the nose started to wobble.  It did not feel like shimmy.  It wobbled a couple times, and then veered to the left.  The right brake was applied to compensate.  The nose dropped six inches with an audible crunch.  The plane skidded down the runway.  The brakes were applied hard and the airplane was kept close to the centerline.

[https://voba.clubexpress.com/clubs/495146/forum_message_images/IMG_20130807_203950%5b1%5d_-1943312893.jpg]


The gear fork failed catastrophically.  It was broken into three pieces.  The wheel was captured by the wheel pant.  It did not go through the prop.

The primary failure was through the thickest part of the casting.  The crack did not follow any visible stress riser.  It did not intersect the gear strut hole.  There was no obvious origin point for the break.

[https://voba.clubexpress.com/clubs/495146/forum_message_images/IMG_20130807_204108%5b1%5d_-1943285437.jpg]


This fork was previously installed on the factory trainer.  It was used during the development and testing of the hydraulic shimmy damper.  When the development and testing was complete, the trainer fork was sent to me along with his damper already installed.  The complete setup was installed on N114MV.  It was on the plane for the first flight.

The plane was flown for 8 months without a nose wheel pant.  On the first flight with a wheel pant, the damper pin sheared resulting in a shimmy.  A new, harder, pin was installed and the plane was flown for another five months without a wheel pant.  The wheel pant was reinstalled and the fork accumulated 30 takeoffs and landings before it failed.

In the 16 months the fork was used on N114MV it did not experience a "nose first" or other notably hard landing.

Gear Fork Failure N568Y -- John Youngblood XL/RG

March 10, 2014. While attempting to land in variable wind conditions in Arizona (AWOS reported 6 kt gusts), the canard stalled over the runway and the nose of the airplane dropped.  When the nose wheel struck the fork split in two places.

 The splits were on either side of the main boss on top of the fork. The fork arms and nose wheel departed the airplane.  The plane came to a skidding stop on the bare nose gear strut.  Ground observation of wind gusts was 0 - 20 kts.

[https://voba.clubexpress.com/clubs/495146/forum_message_images/P1040563_-1942023717.jpeg]


Five years prior, while landing at Sun-N-Fun, the aircraft suffered a violent shimmy (nose landing gear fiber lock nut was loose after tightening two flight segments prior).  The aircraft was inspected by the factory people and no crack or problem was found.  On the trip home John made a stop in Missouri.  During roll out in Joplin, the gear leg failed.  The gear leg was replaced and the plane was flown home.

[https://voba.clubexpress.com/clubs/495146/forum_message_images/P1040562_-1943199995.jpeg]


The new gear leg and original fork have been in use since.

[https://voba.clubexpress.com/clubs/495146/forum_message_images/P1040560_-1941984981.jpeg]


The surface of the gear fork had been polished.

Both forks had years of use.  One was FG one was RG. Both forks had experienced shimmy.  Both failures were sudden and without warning.  Both pilots feel fortunate there were no injuries and damage was localized to the landing gear.

These are the only known Velocity XL gear fork failures in the fleet. Both failures have been discussed with Scott Swing.

The pieces from my fork were shipped to the factory for inspection.  This information has also been shared with other Velocity owners and builders.

Scott Swing has been very helpful.  Both forks had experienced shimmy and at least one very hard landing.  Scott is confident in the current fork.  He understands the failures are personal for John and me and he appreciates our desire to have an even stronger fork.

Richard Cano is flying with a fork milled from billet.  In general, a billet fork will be stronger than a cast fork. Scott Swing suggested 7075 alloy be used.  We are in the process of developing a replacement milled from billet.

When we get closer to producing a fork, we may open the purchase to the community. It would be helpful to have an idea of how many builders and owners would be interested in purchasing the upgraded fork as that would likely impact the cost.

The Velocity factory is not recommending you replace your fork.  I am not recommending you replace your fork.  This has been provided only for your information and consideration.  If you have experienced a shimmy or have a concern about your fork, Scott has indicated he will be available to answer questions.
Andy Millin
amillin at sbcglobal.net<mailto:amillin at sbcglobal.net?subject=re:For%20Your%20Information%20--%20Velocity%20Gear%20Fork>


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