Adding a temporary ferry tank to my RV

[aitor11]

Hi,

I've been working on designing a ferry tank to extend my aircraft endurance for a flight on the Caribbean. The design is pretty much done including how to plug into the fuel system. Since my engine is carburated, I'll be plugging into the unused port of the fuel selector valve.

Now when it comes to making sure that I comply with the rules, I'm trying to fully understand the paperwork implications and how to handle them. From what I see:

Since I'm tapping into the fuel system it looks like it can be considered a major modification

1. Need to notify the FSDO
2. Need 5 hours of flight testing
3. Need to document at least:

• Logbook entry for ferry tank installation
• Updated weight and balance
• Updated fuel-system schematic / operating procedure
• Fuel transfer checklist
• Usable fuel determination
• Ground fuel-flow test
• In-flight transfer test
• Leak check
• Venting check
• Unusable fuel calculation
• Emergency “ferry tank unusable” plan

Am I thinking about it correctly?

Thanks in advance to the experts on the rules for any guidance

Aitor

 

[bjdecker]

Not going to comment on the major / minor modification paper work and what that might entail -- Except be warned, certain FSDO's (SW-17) may require you to jump through flaming hoops and then require inspections (6 month wait), new phase 1 of 40+ hours, and so on...oops -- I commented

On the system design:
Remember 100LL weighs ~+6lbs/gallon -- does the tank have some kind of internal baffling to make sure mass distribution remains constant? Need retention in all three axis for tank + full fuel weight; you don't want the tank coming loose while maneuvering/turbulence.
Ensure the venting is to the outside slipstream with a healthy positive ∆P and not the cabin air.

 

[aitor11]

Not going to comment on the major / minor modification paper work and what that might entail -- Except be warned, certain FSDO's (SW-17) may require you to jump through flaming hoops and then require inspections (6 month wait), new phase 1 of 40+ hours, and so on...oops -- I commented

On the system design:
Remember 100LL weighs ~+6lbs/gallon -- does the tank have some kind of internal baffling to make sure mass distribution remains constant? Need retention in all three axis for tank + full fuel weight; you don't want the tank coming loose while maneuvering/turbulence.
Ensure the venting is to the outside slipstream with a healthy positive ∆P and not the cabin air.

Thank you Brian! Yes, all those aspects are taken into account, installation, weight and balance, venting, baffles, etc. The biggest issue is as you know paperwork!

 

[fixnflyguy]

Perhaps let folks know which "RV" series you are configuring, as I don't see that anywhere. I am aware of at least one RV that has a proven design that works well (RV8 if I recall). Also, various wingtip extended range tanks have been added to others that feed into the wing tanks. It may best to utilize a system that selectively pumps fuel into an existing tank as needed, eliminating the risk of port reassignment and fuel delivery change to the current set-up. I also reserve comment on the Phase 1 scenario as each FSDO agent will likely have their own opinion, and your request may be challenging and time consuming.

 

[Ironflight]

You have a pretty good technical checklist - good for you!

In terms of “paperwork”, that all depends on what YOUYR Operating Limitations say about major modifications. The exact wording regarding notifying or getting permission from the FSDO (or not…) has changed many times over the years, so whatever YOUR Ops Lims says will govern your case. Some say “notify”, some say “notify and get a response”, some don’t say a thing.

The rules governing changes and what an inspector is required to do are so completely different for certified versus Experimntal, and most FSDO inspectors have so little actual experience with Experimental, that you are likely to get a lot of wildly different answers about what is required. The over-arching guidance for inspectors is that if you. Are monkeying aroudn with experimntal, the safety of the general public has to be protected. So long as you’re testing doesn’t put others at risk, they shouldn’t require much else. Shouldn’t….but they might becasue of inexperience.

Read your Ops Lims and see what is minimally required, study up on WHY they are written that way, and THEN talk to the FSDO (if required).

 

[aitor11]

Thank you Paul. I'm looking at them now to try to better understand.

 

[aitor11]

Re-reading the Operations Limitations this is the wording I have on mine:

12. After incorporating a major change as described in 21.93, the aircraft owner is required to reestablish compliance with 91.319(b) and notify the geographically responsible FSDO of the location of the proposed test area. The aircraft owner must obtain concurrence from the FSDO as to the suitability of the proposed test area.

After that it goes into:

If the major change includes installing a different type of engine (reciprocating to turbine) or a change of a fixed-pitch from or to a controllable propeller, the aircraft owner must fill out a revised FAA Form 9130-6 to update the aircraft's file in the FAA Aircraft Registration Branch, AFS-750. All operations must be conducted under day visual flight rules (VFR) conditions over a sparsely populated area in compliance with 91.305. The aircraft must remain in flight test for a minimum of 5 hours. The FSDO may require addition time (more than 5 hours) depending on the extent of the modification.

and it closes with:

Persons nonessential to the flight must not be carried. The aircraft owner must make an aircraft maintenance record entry describing the change before the test flight. Following satisfactory completion of the required number of flight hours in the flight test area, the pilot must certify in the records that the aircraft has been shown to comply with 91.319(b). Compliance with 91.319(b) must be recorded in the maintenance records with the following, or a similarly worded statement: "I certify that the prescribed flight test hours have been completed and the aircraft is controllable through its normal range of speeds and thorough all maneuvers to be executed, has no hazardous characteristics or design features , and is safe for operation"(23)

The airplane is still based within the original test area. My understanding is that the test area suitability is the most important thing to confirm with the FSDO, am I reading it correctly?

Aitor

 

[Mel]

You are reading correctly! Give me a call 972-784-7544.