Guys, I just got a call from a friend who is working with a DAR to get his plane inspected this weekend. The DAR is requesting FAA 90-89A Advisory Circular, what is this? From what I was told it is to prove that the fuel system, the plane has to be tested and requires that in some cases you have to raise the nose of the airplane 15 to 20 degrees and make sure there is enough fuel to the engine in a climb. The aircraft is a 7A with fuel injection, what obligation does he have to prove this.
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FAA 90-89-A
- Thread starter Adam
- Start date
frazitl
Well Known Member
i did this on my 7a
It was worth the effort imho. One less ? on my mind for that first flight. I first tested fuel rate in the hangar with the nose very high.
Shortly b4 first flight, i tied down the tail hook to an airport tie down(nose way up in the air) and did a high power run up. Pretty exciting, but all went well. Be certain that the ground tie down is stronger than it has to be!
It was worth the effort imho. One less ? on my mind for that first flight. I first tested fuel rate in the hangar with the nose very high.
Shortly b4 first flight, i tied down the tail hook to an airport tie down(nose way up in the air) and did a high power run up. Pretty exciting, but all went well. Be certain that the ground tie down is stronger than it has to be!
Last edited:
It's a good idea, but not required
My read of the text, and Chapter 11, is that while it's not a hard and fast requirement, it's another good method to reduce risk in flight.
"e. Fuel Flow and Unusable Fuel Check: This is a field test to ensure the aircraft engine will get enough fuel to run properly, even if the aircraft is
in a steep climb or stall attitude.
(1) First, place the aircraft?s nose at an angle 5 degrees above the
highest anticipated climb angle. The easiest and safest way to do this
with a conventional gear aircraft is to dig a hole and place the aircraft?s
tail in it. For a nose gear aircraft, build a ramp to raise the nose gear to
the proper angle.
(2) Make sure the aircraft is tied-down and chocked. With minimum fuel
in the tanks, disconnect the fuel line to carburetor. The fuel flow with
a gravity flow system should be 150 percent of the fuel consumption
of the engine at full throttle. With a fuel system that is pressurized,
the fuel flow should be at least 125 percent. When the fuel stops
flowing, the remaining fuel is the ??unusable fuel?? quantity.
(3) Since the fuel consumption of most modern engines is approximately
.55 pounds per brake horsepower per hour for a 100 horsepower
engine, the test fuel flow should be 82.5 pounds (13.7 gallons)
per hour for gravity feed, or 68.75 pounds (11.5 gallons) per
hour for a pressurized system. The pounds per hour divided by 60
equals 1.4 pounds and 1.15 pounds per minute fuel rate respectively.
NOTE: Formula for fuel flow rate gravity feed is .55 x engine
horsepower x 1.50 = pounds of fuel per hour divided by 60 to
get pounds per minute, divided by 6 to get gallons per minute. For
a pressurized system, substitute 1.25 for 1.50 to determine fuel flow rate."
My read of the text, and Chapter 11, is that while it's not a hard and fast requirement, it's another good method to reduce risk in flight.
"e. Fuel Flow and Unusable Fuel Check: This is a field test to ensure the aircraft engine will get enough fuel to run properly, even if the aircraft is
in a steep climb or stall attitude.
(1) First, place the aircraft?s nose at an angle 5 degrees above the
highest anticipated climb angle. The easiest and safest way to do this
with a conventional gear aircraft is to dig a hole and place the aircraft?s
tail in it. For a nose gear aircraft, build a ramp to raise the nose gear to
the proper angle.
(2) Make sure the aircraft is tied-down and chocked. With minimum fuel
in the tanks, disconnect the fuel line to carburetor. The fuel flow with
a gravity flow system should be 150 percent of the fuel consumption
of the engine at full throttle. With a fuel system that is pressurized,
the fuel flow should be at least 125 percent. When the fuel stops
flowing, the remaining fuel is the ??unusable fuel?? quantity.
(3) Since the fuel consumption of most modern engines is approximately
.55 pounds per brake horsepower per hour for a 100 horsepower
engine, the test fuel flow should be 82.5 pounds (13.7 gallons)
per hour for gravity feed, or 68.75 pounds (11.5 gallons) per
hour for a pressurized system. The pounds per hour divided by 60
equals 1.4 pounds and 1.15 pounds per minute fuel rate respectively.
NOTE: Formula for fuel flow rate gravity feed is .55 x engine
horsepower x 1.50 = pounds of fuel per hour divided by 60 to
get pounds per minute, divided by 6 to get gallons per minute. For
a pressurized system, substitute 1.25 for 1.50 to determine fuel flow rate."
fuel flow test
This is one of the "hot topics" from the NTSB regarding EAB accidents. They claim that a large percentage of EAB engine failures are due to fuel system problems.
In reasearching 2009 EAB accidents, I only found ONE accident that was certainly caused by a fuel problem. This was a flying aircraft that had a history of tank leaks and the metal tanks were improperly sealed with a material that did not bond and blocked the fuel system.
When a pilot puts a ram air fuel cap on backwards or leaves a ground cover on a fuel vent, these are not problems that will be "solved" by ground fuel flow testing. They are also not EAB problems but are operator problems. The fuel tests in AC90-89A should certainly be done for a gravity flow system. The static fuel flow doesen't apply in most cases to a system with fuel pumps. The full power test is a good idea but not something I want to do with a proven fuel system design and a newly overhauled engine.
This is one of the "hot topics" from the NTSB regarding EAB accidents. They claim that a large percentage of EAB engine failures are due to fuel system problems.
In reasearching 2009 EAB accidents, I only found ONE accident that was certainly caused by a fuel problem. This was a flying aircraft that had a history of tank leaks and the metal tanks were improperly sealed with a material that did not bond and blocked the fuel system.
When a pilot puts a ram air fuel cap on backwards or leaves a ground cover on a fuel vent, these are not problems that will be "solved" by ground fuel flow testing. They are also not EAB problems but are operator problems. The fuel tests in AC90-89A should certainly be done for a gravity flow system. The static fuel flow doesen't apply in most cases to a system with fuel pumps. The full power test is a good idea but not something I want to do with a proven fuel system design and a newly overhauled engine.
Epepperman
Member
Fuel flow test
The DAR is requesting FAA 90-89A Advisory Circular,
The first paragraph
1. PURPOSE. This advisory circular (AC) sets
forth suggestions and safety related recommendations
to assist amateur and ultralight builders in
developing individualized aircraft flight test plans.
I was told it is to prove that the fuel system, the plane has to be tested and requires that in some cases you have to raise the nose of the airplane 15 to 20 degrees This is not stated anywhere. It does state all angles of attack, should you turn your airplane upside down to satisfy this test, oh noooo.
I would challange him on this but state you'll test this in the first 40 hours.
If he insists I would tell him your going elsewhere. Making up the law is not his job.
The DAR is requesting FAA 90-89A Advisory Circular,
The first paragraph
1. PURPOSE. This advisory circular (AC) sets
forth suggestions and safety related recommendations
to assist amateur and ultralight builders in
developing individualized aircraft flight test plans.
I was told it is to prove that the fuel system, the plane has to be tested and requires that in some cases you have to raise the nose of the airplane 15 to 20 degrees This is not stated anywhere. It does state all angles of attack, should you turn your airplane upside down to satisfy this test, oh noooo.
I would challange him on this but state you'll test this in the first 40 hours.
If he insists I would tell him your going elsewhere. Making up the law is not his job.
