We verified oil temperature bulb resistance readings for a reference to indicated temps.
Sitting static on a warm day we found 100Ω to be 30 degrees.
We didn't know the range that the bulb might have. The first try at 200Ω was invalid. We found just a sight change in resistance would make the indication change. A 5Ω increase in resistance gave use a 10 degree rise in indication. I would imagine full scale hot/cold would be a pretty tight range of resistance (let's guess 80Ω to 120Ω)??
There are many times when we have Pitot/Static leaks in lines or fittings that have to be located and replaced.
The usual practice is to isolate the line and apply pressure to it. We then use leak detector to find the problem area (presence of bubbles).
Using this method, there is always a concern of over-pressurizing the lines and splitting one open. I've used more, but ≈ 5 PSI usually is enough pressure to locate leaks.
A low pressure regulator with nitrogen can be used, but we usually just use the Pitot/Static Test Box. Using the pitot output only..... 400 Knots is a common setting.
The question arises as to what 400 Knots is equivalent to in PSI. We use a Barfield DPS1000. The display can be changed to show different units of measure.
Knots to inches of mercury (inHg).....
The tester shows two values for inHg, Pt and Qc. A little digging was required to find the difference.....
Impact Pressure (Qc) is the pressure a moving stream of air produces against a surface that brings part of the moving stream to rest. It is the difference between the total pressure (Pt) and the static pressure (Ps). These pressure properties are related by the formula: Qc = Pt - Ps (From Mensor.com)
The link above is worth a look. Needless to say, we want to reference Qc. Using a online conversion, we found the value 8.38 inHg to be a little over 4 PSI.
The explanation above is wrong dealing with the flapper.
When a blower is operating..... it pulls "its own" flapper flush to the mount. This isolates the plenum and the secondary blower system from the airflow. All air is drawn from the tubes on the cargo pit ceiling. Air is pulled through "both" sensors and then exits the running blower.
In other words..... it the flapper fails on the running blower, air is drawn backwards through the non-running blower and not through the tubes and sensors.
We still don't think in terms of "quality". A electric pump can either do the job or it can't. If you've changed the pump and still have the same issues, you could have a electrical issue or possibly an hydraulic power output issue.
Has anyone done the simple stuff? Are all three phases there? Have you put an Amp Clamp on each phase to make sure they're pulling the same amps? Have you tried another source of power input?
These are basic things to check. Don't think in terms of quality..... try quantity (amperage power).
We don't normally check power "quality". You can look at it with a O'Scope, but that's just going to show a sine wave.
You have three sources of power on the 737. Each engine driven generator and a APU generator. These can be isolated to power the complete aircraft if you wanted to try each one individually.
On a previous post I sent a copy of the maintenance manual that stated the electrical pump can "only" supply six gallons a minute and it is "not" recommended for raising the gear. The manual stated it can raise one gear at a time when the aircraft is on jacks.
What is the problem here??? Is a engine pump not working??? Crews are not supposed to use the electric pump for raising the gear. After takeoff, the gear should go up quickly as they cause significant drag. I haven't dug into (nor will I) if either primary hydraulic system can be used to lift the gear.
If an aircraft cannot lift the gear with the engine pumps..... it should be grounded until fixed.
You're travelling down the wrong road with your thinking.
Proximity and micro-switches show position. Speed sensors do exactly as the name says..... output a rotational speed.
On a gear assembly there are wheel speed sensors for Auto-Bakes/Anti-Skid, brake temp sensors, gear tilt sensors (if four or more tires per gear), brake fans (if equipped), squat switches (for weight on wheels), and gear position switches (either micro or proximity).
Not all gear have every item listed above, but you can understand the amount of wiring to support all these.
You're comparing apples to oranges as far as functions go. Each item has its own use. Each item has its own wires.