If a Pitot Static system is leaking what would happen to the indicating instruments,(ALT,VSI and ASI)?

Question

Could someone describe what would happen if the Pitot Static system is leaking and what would happen to the indicating instruments due to the leakage of the pitot, e.g. Altimeter, Vertical speed indicator and Airspeed indicator
(ALT,VSI and ASI) for planes like boeing 737 or any other flights

Answer 1

Okay, Thomaswheeler- don't fix my airplane ever. You have NOOOOOO Clue.

Think of them as two different systems. Pitot System and Static System.
The one's dude's super long copy and paste definition is correct, but I'll try to simplify it.
1st you want to know about a indicating instrument leak. Or Instrument hosing/fitting leak.
Well leaks, your readings will be lower in altitude if you have a static leak, but not that seriously low, but since your talking about a B737 a noticeable split between the pilots and co-pilots systems. But that would be older airplanes. Current airplanes are ran by Air Data computers and digital altimeters and airspeeds and are as accurate as all get out RVSM Standards. The Auxilliary Instruments- a spare third set would have readings that are off.
As far as pitot clog ups and freeze overs, well that is not a leak. But for clog ups or moisture being caught up in the system and freezing, your airspeed will pretty much just back pressure and read zero.
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Okay unpressurized airplanes- you won't see a static leak. Only if you pressurize the system with a proper pitot/static tester can you find out if you have a leak. And Pitot systems do not need to be verified for 91.411 and 91.413 IFR Recertifications every 24 months.. It isn't in the FARS. But most likely a bug gets caught and you will see erratic-low or no airspeed. (They call it a pitot-Static test, but it's actually an altimeter-transponder recertification). Then we pump up the aircraft to whatever certification altitude and make sure the transponder is transponding the same altitude to ATC.
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And your Mechanic cannot easily fix a static leak on your airplane legally. Sorry. Only a Repair Station Technician (Thus Avionics Guy- ME) with Pitot-Static Ratings can repair-test and recertify your altimeter system legally. And it usually isn't easy, especially if its an old aircraft with old hoses and fittings and rigged up instruments.
Happy Flying

Answer 2

Pitot Static Instruments

Answer 3

If you have a leak in the peto static system, then the readings of your instruments will be very unreliable. The altimeter and VSI do not require peto pressure so a leak on that side would not impact and unless the Static leak is located in an area of turbulent air which generates a lower or higher pressure in the static system, they will not be affected. The airspeed totally relies on peto pressure to give you an accurate air speed reading, a leak here Will give you a lower reading. A minor leak could go undetected for a long time, though when you are at cruising altitude and your engine RPMs are set for cruise and your ASI reads significantly lower than the normal cruise speed, chances are you have a significant leak.

Answer 4

If only the pitot system is leaking, the only affected instrument would be the airspeed indicator (because altimeters and VSIs use only static, not pitot air). Depending on where the leak is, it could cause the instrument to read low (lower diff p between RAM and static) or zero.

Answer 5

Pitot-Static Systems
Three basic pressure-operated instruments are found in most
aircraft instrument panels. These are the sensitive altimeter,
airspeed indicator (ASI), and vertical speed indicator (VSI).
All three receive the pressures they measure from the aircraft
pitot-static system.
Flight instruments depend upon accurate sampling of the
ambient atmospheric pressure to determine the height and
speed of movement of the aircraft through the air, both
horizontally and vertically. This pressure is sampled at two
or more locations outside the aircraft by the pitot-static system.
The pressure of the static, or still air, is measured at a flush
port where the air is not disturbed. On some aircraft, this air
is sampled by static ports on the side of the electrically heated
pitot-static head, . Other aircraft
pick up the static pressure through flush ports on the side of
the fuselage or the vertical fin. These ports are in locations
proven by flight tests to be in undisturbed air, and they are
normally paired, one on either side of the aircraft. This dual
location prevents lateral movement of the aircraft from giving
erroneous static pressure indications. The areas around the
static ports may be heated with electric heater elements to
prevent ice forming over the port and blocking the entry of
the static air.
Pitot pressure, or impact air pressure, is taken in through an
open-end tube pointed directly into the relative wind flowing
around the aircraft. The pitot tube connects to the airspeed
indicator, and the static ports deliver their pressure to the
airspeed indicator, altimeter, and VSI. If the static ports should
ice over, or in any other way become obstructed, the pilot is
able to open a static-system alternate source valve to provide
a static air pressure source from a location inside the aircraft.
This may cause an inaccurate indication on the
pitot-static instrument. Consult the Pilot’s Operating
Handbook/Airplane Flight Manual (POH/AFM) to determine
the amount of error.

Airspeed Indicators
An airspeed indicator is a differential pressure gauge that
measures the dynamic pressure of the air through which the
aircraft is flying. Dynamic pressure is the difference in the
ambient static air pressure and the total, or ram, pressure
caused by the motion of the aircraft through the air. These
two pressures are taken from the pitot-static system.



Vertical Speed Indicators (VSI)
The vertical speed indicator (VSI) is also called
a vertical velocity indicator (VVI) and was formerly known
as a rate-of-climb indicator. It is a rate-of-pressure change
instrument that gives an indication of any deviation from a
constant pressure level.

Inside the instrument case is an aneroid very much like the
one in an airspeed indicator. Both the inside of this aneroid
and the inside of the instrument case are vented to the static
system, but the case is vented through a calibrated orifice
that causes the pressure inside the case to change more slowly
than the pressure inside the aneroid. As the aircraft ascends,
the static pressure becomes lower and the pressure inside the
case compresses the aneroid, moving the pointer upward,
showing a climb and indicating the number of feet per minute
the aircraft is ascending.
When the aircraft levels off, the pressure no longer changes,
the pressure inside the case becomes the same as that inside
the aneroid, and the pointer returns to its horizontal, or zero,
position. When the aircraft descends, the static pressure
increases and the aneroid expands, moving the pointer
downward, indicating a descent.
The pointer indication in a VSI lags a few seconds behind
the actual change in pressure, but it is more sensitive than an
altimeter and is useful in alerting the pilot of an upward or
downward trend, thereby helping maintain a constant altitude.

Some of the more complex VSIs, called instantaneous vertical
speed indicators (IVSI), have two accelerometer-actuated air
pumps that sense an upward or downward pitch of the aircraft
and instantaneously create a pressure differential. By the time
the pressure caused by the pitch acceleration dissipates, the
altitude pressure change is effective.


Sensitive Altimeter
A sensitive altimeter is an aneroid barometer that measures
the absolute pressure of the ambient air and displays it in
terms of feet or meters above a selected pressure level.
The sensitive element in a sensitive altimeter is a stack of
evacuated, corrugated bronze aneroid capsules like those
The air pressure acting on these aneroids
tries to compress them against their natural springiness, which
tries to expand them. The result is that their thickness changes
as the air pressure changes. Stacking several aneroids
increases the dimension change as the pressure varies over
the usable range of the instrument.
A sensitive altimeter is one with an adjustable barometric
scale that allows you to set the reference pressure from which
the altitude is measured. This scale is visible in a small
window, called the Kollsman window. The scale is adjusted
by a knob on the instrument. The range of the scale is from
28.00 to 31.00" Hg, or 948 to 1,050 millibars.
Rotating the knob changes both the barometric scale and the
altimeter pointers in such a way that a change in the
barometric scale of 1" Hg changes the pointer indication by
1,000 feet. This is the standard pressure lapse rate below 5,000
feet. When the barometric scale is adjusted to 29.92" Hg, or
1,013.2 millibars, the pointers indicate the pressure altitude.
When you wish to display indicated altitude, adjust the
barometric scale to the local altimeter setting. The instrument
then indicates the height above the existing sea level pressure.

The pitot system can become blocked completely or
only partially if the pitot tube drain hole remains open.
If the pitot tube becomes blocked and its associated
drain hole remains clear, ram air no longer is able to
enter the pitot system. Air already in the system will
vent through the drain hole, and the remaining pressure
will drop to ambient (outside) air pressure. Under these
circumstances, the airspeed indicator reading decreases
to zero, because the airspeed indicator senses no
difference between ram and static air pressure. The
airspeed indicator acts as if the airplane were stationary
on the ramp. The apparent loss of airspeed is not
usually instantaneous. Instead, the airspeed will drop
toward zero.

If the pitot tube, drain hole, and static system all
become blocked in flight, changes in airspeed will not
be indicated, due to the trapped pressures. However, if
the static system remains clear, the airspeed indicator
acts as an altimeter. An apparent increase in the ram air
pressure relative to static pressure occurs as altitude
increases above the level where the pitot tube and drain
hole became blocked. This pressure differential causes
the airspeed indicator to show an increase in speed. A
decrease in indicated airspeed occurs as the airplane
descends below the altitude at which the pitot system
became blocked.
be indicated, due to the trapped pressures. However, if
the static system remains clear, the airspeed indicator
acts as an altimeter. An apparent increase in the ram air
pressure relative to static pressure occurs as altitude
increases above the level where the pitot tube and drain
hole became blocked.
If the static system becomes blocked but the pitot tube
remains clear, the airspeed indicator continues to
operate; however, it is inaccurate. Airspeed indications
are slower than the actual speed when the airplane is
operated above the altitude where the static ports
became blocked, because the trapped static pressure is
higher than normal for that altitude. When operating at
a lower altitude, a faster than actual airspeed is
displayed due to the relatively low static pressure
trapped in the system.
A blockage of the static system also affects the altimeter
and VSI. Trapped static pressure causes the altimeter to
freeze at the altitude where the blockage occurred. In
the case of the VSI, a blocked static system produces a
continuous zero indication.

Answer 6

b is the main the terrific option answer a) maximum airplane have a squat swap that reduces the capacity to the heater components so it is not significant how long that's on. c) might desire to be mind-blowing for some airplane yet definately not the cessnas

Answer 7

erronious inconsistant readings not reliable in flight, easily correctable on the ground by a qualified mechanic

Answer 8

Well basicley the instroments would stop working this would mean that the piolot whould have not artifual herizan no alt vsi etc esc... They would be helped out by atc and the atc would prep the airport for the emergency. once the plane had landed this would be repaired ASAP because as the saying goes "if its not in the air its not making money" however verus cheaks would be made before it was allowed to contine

I hope this helps
Tom

Answer 9

ALT: normal
VSI : normal
ASI : underreads