Floorboard questions

[Allen B]

Hello folks. I have a model 5 QBK. My kit came with floorboards that basically fit perfectly. Just a couple areas that need a small amount of adjustments. They overlap in one spot. The cargo area to the rear seat. I’ve read some people just let them overlap and do not make doublers there. Is this an acceptable practice? I plan on using carpet so I’m okay with the cosmetic issues. I feel like there’s enough material overlapping that it should add plenty of rigidity to that area.

What are people doing for pilot/co-pilot seats? Just adding a doubler between the two?

Thanks for the advice

Allen

[Battson]

"Acceptable practice" is ill-defined for floorboards. Everything from bare wood to carbon fibre with deco-dot matting over the top is acceptable and commonly used in certified aircraft. What works best should be informed by your mission, and then your time, budget, and finally personal tastes

Some overlap between boards is good, as it is stronger and leaves no gap for detritus to get through - when you place a big load on them, they move a lot, gaps can open up. However, too much overlap makes them hard to remove without removing the next floorboard, or bending things a lot, which risks damage to the interior. Therefore, I advocate cutting the boards under the front seats in half down the axis of the fuselage, making doublers to join floorboards with nut-plates each side, so either side can be removed individually. You may like to do the same in other areas, depending on your flooring design.

Access is so easy with the plan uncovered and in bits, when it's all assembled it gets a lot harder and more onerous. Shortcuts are your friend. Pulling the whole floor is a huge job. While it's easy when building, partial flooring makes a lot more sense once the plane is finished and flying.

Carpet is a good thing as it holds dust and detritus so you can vacuum it up later. However, it also holds water (if you put wet things in the plane, often) and can lead to corrosion in wet areas - such as near the cargo door (wet cargo) or where wet boots / shoes often rest. Some stainless steel plate over the carpet in the pilot footwell is a good idea. Fasteners are especially susceptible to corrosion. Wooden floorboards with stainless fasteners are common in seaplanes for this reason.

[Allen B]

Thank you for this information. The newer kits come with the front seat floor boards cut in half from the factory. All that’s needed is to make the doubler underneath which is very helpful. I will make the doublers for sure and I will definitely take your advice with the kick panels.

Do you have a recommendation on hardware to attach the floorboards? I’ve heard that clips can lead to loud noises; whereas nut plates are more permanent and can be quieter? Can you speak to this?

I appreciate the advice. Thanks, Allen

[gregc]

My 2 cents worth - There is no significant difference in vibration/noise. In fact the noise level in a Bearhawk is so high you might not notice a brass band in the rear seat ;-). Tinnermans and clip nuts (Monadnock clips) are faster to install than nut plates but can be dropped into small places when installing/re-installing the floor boards. Tinnermans are the least expensive, nut plates next and clip nuts the most expensive. I used nut plates but would use tinnermans the next time.

[Allen B]

Sir, I appreciate your 2 cents. I’m certainly not trying to cut corners but if people have had success with Tinnermans I’m open to using them. If noise isn’t a factor with either that’s very useful information. I’m a first time builder. My goal is to keep it as simple as possible the first build. Thank you very much for your advice.

[Battson]

Thank you for this information. The newer kits come with the front seat floor boards cut in half from the factory. All that’s needed is to make the doubler underneath which is very helpful. I will make the doublers for sure and I will definitely take your advice with the kick panels.

Do you have a recommendation on hardware to attach the floorboards? I’ve heard that clips can lead to loud noises; whereas nut plates are more permanent and can be quieter? Can you speak to this?

I appreciate the advice. Thanks, Allen

I used nut-plates and it is a lot more work to install, especially seeing as the floor is rarely removed once the machine is finished and flying. However they are a much more permanent and tidy solution, they can't be bumped loose like tinnerman washers and end up bouncing around in the belly with the pulleys and control cables.

Nut-plates also allow the floorboards to sit flush on the fuselage tube structure, which does effectively prevent vibration / noise from the floorboards. Carpet also goes a long way to entirely preventing all noise and vibration. My OEM aluminium flooring, under carpet, has never made any noise - ever. It's also plenty strong enough for all reasonable cargo / loads I've come across.

The rear bulkhead, whether aluminium or plastic or composite, does vibrate a lot and often does make a lot of noise. It also shakes when propwash comes in windows / doors and makes a lot of noise. That is one thing which needs a dampener / stiffener.

[Battson]

Sorry I also should have put in some context, you will literally require many hundreds of nutplates in the wings and boot cowl around the instrument panel and access hatches in the belly / gear leg area. An extra 20 or 30 for the floorboards, it's not a lot of incremental work - just make sure you use templates and very sharp drill bits if you do However I think tinnerman washers are a fine solution, too.

[Jhankins]

I used tinnerman clips to attach my floorboards, they are definitely the quickest/cheapest option, a close second would be rivnuts. Nutplates definitely the most expensive and time consuming, but also the most rigid option in my opinion. In the time it takes to drill all those holes and countersink the 4130 fuselage tabs (a major pain) you could have removed/installed the floorboards a dozen times had you used one of the other two fastening options. No real right or wrong way just all depends on how you value your time

[rv8bldr]

Exactly what I did. With a small fortunes worth of nutplates in the wings, I wanted to save somewhere :-) But, as you say, dead simple to install and use.

[svyolo]

You can also use "bigger" nutplates or clipnuts etc for non-structural baggage hold down. Like netting to keep smallers stuffing from sliding around. I have 6 or 8 with 10-32 screws holding down stainless eyelets. These are not strong enough for primary cargo hold down heavy stuff, but they are convenient.

1/4" are also available.

[jaredyates]

I remove the floorboards from the stick assembly aft at each condition inspection, so that I can see and lubricate the control cables that pass under the floor and check for unwanted material. I had a friend that purchased a minimally-maintained Citabria, and the entire area between the belly fabric and the floorboards was packed with hangar insulation, leaves, and other stuff packed in by mice. There were also some snake skins but it wasn't clear if those were put there by the mice or if it was a whole circle of life of snakes coming in to eat the mice.

In our first plane we used 8-32 clip nuts, and the second plane has #8 stainless screws with tinnerman nuts. I have come to appreciate the latter, because they never seem to have any thread problems.

[Allen B]

Thank you all for your help.