737 Classic engine anti-ice
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737 Classic engine anti-ice
Questions regarding the ant-ice operation of the Classic 737: (1)The switch is electrically operated. The valve itself is pneumatically operated. What is the source of the air to operate to operate the valve?. (2)The heated air enters the cowl, but surely there must be a constant flow of this heated air to do the job of heating the cowl.Where does the air 'expel'?. And while I have your attention, exactly what does get heated up, and not heated up on the engine?Thanks ahead
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Bleed air from the 8th stage is used to feed hot air into the right and left sides of a common shroud. From there the air flows through the inlet guide vanes, circulates in the nose dome where it anti-ices the PT2 probe and then is ejected through the nose dome. This air then is ingested in the engine.
More air, from the 13th stage, is fed to the nose cowl. It circulates inside the cowl and then is ejected via into the ram inlet.
So, the inlet guide vanes, the nose dome, PT2 probe and cowl.
Next?
More air, from the 13th stage, is fed to the nose cowl. It circulates inside the cowl and then is ejected via into the ram inlet.
So, the inlet guide vanes, the nose dome, PT2 probe and cowl.
Next?
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how does the valve operate?
Thanks Wileydog3 & yachno1: I now understand the flow.---- Regarding the switch itself, my little info book says it sourced from DC bus 1, with the valve being pneumatic. Maybe I am getting 'way over my head', but I am curious. Is the valve itself electrically moved into position, or does a solenoid open/close causing air to move the valve ?----Thanks again
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BTW, I am well into my 60's, retired refinery technician, held Pvt/Instr /SEL. With about 5 hours in 737-200 simulator. However, over the last 6 years, I have spent a lot of time studying the 737-300 with VCR tapes, study guides,CBT, etc etc. Find it to be incredibly interesting, and also keeps my brain functioning.One must keep busy during their retirement years!! Just thought I'd pass this along
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Thanks Wileydog3 & yachno1: I now understand the flow.---- Regarding the switch itself, my little info book says it sourced from DC bus 1, with the valve being pneumatic. Maybe I am getting 'way over my head', but I am curious. Is the valve itself electrically moved into position, or does a solenoid open/close causing air to move the valve ?----Thanks again
Some valves are electrically held open and some held closed. In the event of an electrical failure, some remain in the last commanded position, some fail open and some fail closed.
I'll get back to you... and good for you doing mental exercises. From what I understand, the brain is a mental muscle.. use it or lose it.
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Hi wileydog3, the question was about the CLASSIC 737.
You must probably be giving info about NG, a common misunderstanding on pprune between CL and NG.
I'm getting lazy these days, so I'll just quote the maintenance manual:
_N_L_E_T_ _C_O_W_L_ _A_N_T_I_-_I_C_I_N_G_ _S_Y_S_T_E_M_ _-_ _D_E_S_C_R_I_P_T_I_O_N_ _A_N_D_ _O_P_E_R_A_T_I_O_N_
1 . G_e_n_e_r_a_l_ (Fig. 1)
A. The inlet cowl anti-icing system is a thermal system using engine hot
bleed air from the 5th and 9th-stages of the high pressure compressor
(HPC) section. The function of the system is to maintain ice free inlet
cowl surfaces during flight and ground operations.
B. The system consists of ducting, a dual purpose pressure regulating and
shutoff valve, a pressure switch and an overheat switch downstream of the
valve, an anti-icing distribution spray ring located in the lip of the
inlet cowl, and an exhaust port located at the 6 o'clock position on the
inlet cowl.
C. Each engine anti-ice system operates independently. Each valve is
pneumatically operated and electrically controlled by a switch located on
the pilots' overhead panel. The associated valve position indicator
lights and warning lights are located adjacent to the switches.
2 . T_h_e_r_m_a_l_ _A_n_t_i_-_I_c_e_ _(_T_A_I_)_ _V_a_l_v_e_ (Fig. 2 and 3)
A. The TAI valve, located at the 1:30 o'clock position (aft looking forward)
on the fan frame, is line mounted in the TAI ducting and is secured with
V-band couplings. The valve is air operated and is set to regulate
outlet pressure at 50 |3 psi. The valve is fully open at inlet pressures
of 10 to 47 psi. The unit consists of a normally closed butterfly
shutoff valve, a normally open pressure regulator butterfly valve, a
servo pilot valve and associated components which form an insulated air
duct section. If the pressure regulator valve fails to regulate the
pressure, the shutoff valve will maintain the pressure at 75 |10 psi.
B. A manual override provision is incorporated in the valve for direct
mechanical operation and for locking the valve in a partially open
position in the event of system malfunction. The valve is designed to
fail in the closed position. The valve incorporates two position
switches to provide valve position indication in the cockpit.
C. The pressure regulator valve is spring loaded in the valve open
direction. Inlet pressure P1 is admitted through restrictor orifices 1
and 2 to the actuator piston chambers. When the pressures in both
chambers are equal, the actuating mechanism tends to open the valve.
D. The shutoff valve is spring loaded in the valve closed direction.
Downstream pressure P2 is directed through the ground test supply shuttle
valve into both actuator piston chambers. Downstream pressure P2 is also
admitted through a restrictor orifice into the overpressure pilot valve.
The actuating mechanism maintains the valve in the closed position when
the solenoid pilot valve is de-energized.
E. The pressure regulator valve and shutoff valve both have provisions for
manual override by means of external wrenching flats on the valve
position indicators. The pressure regulator may be locked in the open
position by replacing the closed position adjustment setscrew with a
locking screw. The shutoff valve may be locked in either the closed or
midposition by inserting a quick-release pin into the lock hole provided
in the valve cover.
MAINTENANCE MANUAL
F. To lock the pressure regulator valve in the open position, first the
valve clamps must be loosened and the valve hardware must be removed.
Then the valve must be turned until the closed position adjustment
setscrew can be removed and replaced with the locking screw. After the
locking screw is installed, the valve must be aligned and the hardware
and clamps installed.
3 . T_h_e_r_m_a_l_ _A_n_t_i_-_I_c_e_ _(_T_A_I_)_ _P_r_e_s_s_u_r_e_ _S_w_i_t_c_h_
A. The TAI pressure switch senses pressure from a pressure tap in the TAI
ducting downstream of the valve. The function of the switch is to act as
a check on the operation of the valve to prevent overpressurizaton of the
inlet cowl. The switch is set to activate at 65 |3 PSI, and provides
cowl overpressure warning indication by illuminating an amber COWL
ANTI-ICE warning light in the cockpit.
4 . T_h_e_r_m_a_l_ _A_n_t_i_-_I_c_e_ _(_T_A_I_)_ _O_v_e_r_h_e_a_t_ _S_w_i_t_c_h_
A. The TAI overheat switch senses temperature in the TAI ducting downstream
of the valve. The switch is set to activate at 825 |20¡F and will
indicate an overtemperature condition by illuminating the master caution,
anti-ice annunciator lights, and an amber COWL ANTI-ICE warning light in
the cockpit. The unit consists of a thermostatic sensor that actuates a
single-pole, single-throw switch.
5 . O_p_e_r_a_t_i_o_n_ (Fig. 3)
A. Functional Description
(1) When the ENG ANTI-ICE switch is positioned to ON for the selected
engine, 28v dc is supplied to the TAI valve. The valve solenoid is
energized and hot air is directed through the valve to the air
distribution spray ring which contains holes that direct the
anti-icing air to the inner lip of the inlet cowl. The air is
circulated around the inlet cowl and vented overboard through the
TAI exhaust port.
(2) When the ENG ANTI-ICE switch is positioned to OFF, the valve
solenoid is de-energized and the valve closes.
(3) When the ENG ANTI-ICE switch is first positioned to ON, the blue
COWL VALVE OPEN light comes on bright to indicate valve in transit.
When the valve reaches the full open position, the light dims.
(4) When the ENG ANTI-ICE switch is moved to OFF, the blue COWL VALVE
OPEN light comes on bright to indicate valve in transit, then goes
off to indicate valve closed.
(5) When a pressure of 65 |3 psi is sensed by the TAI pressure switch,
the switch is activated causing the amber COWL ANTI-ICE warning
light to come on.
(6) When a temperature of 825 |20¡F is sensed by the TAI overheat
switch, the switch is activated causing the amber COWL ANTI-ICE
warning light to come on.
(7) If the engine is not running and the ENG ANTI-ICE switch is set to
ON, the COWL VALVE OPEN light will come on bright and will stay on.
Under these conditions, if the pneumatic system is pressurized, the COWL VALVE OPEN light may become dim momentarily.
One last note; DC Bus1 for engine 1, DC Bus 2 for engine2.
And hot air is not ingested, it's ducted overboard from the bottom of the cowl lip.
LEM
You must probably be giving info about NG, a common misunderstanding on pprune between CL and NG.
I'm getting lazy these days, so I'll just quote the maintenance manual:
_N_L_E_T_ _C_O_W_L_ _A_N_T_I_-_I_C_I_N_G_ _S_Y_S_T_E_M_ _-_ _D_E_S_C_R_I_P_T_I_O_N_ _A_N_D_ _O_P_E_R_A_T_I_O_N_
1 . G_e_n_e_r_a_l_ (Fig. 1)
A. The inlet cowl anti-icing system is a thermal system using engine hot
bleed air from the 5th and 9th-stages of the high pressure compressor
(HPC) section. The function of the system is to maintain ice free inlet
cowl surfaces during flight and ground operations.
B. The system consists of ducting, a dual purpose pressure regulating and
shutoff valve, a pressure switch and an overheat switch downstream of the
valve, an anti-icing distribution spray ring located in the lip of the
inlet cowl, and an exhaust port located at the 6 o'clock position on the
inlet cowl.
C. Each engine anti-ice system operates independently. Each valve is
pneumatically operated and electrically controlled by a switch located on
the pilots' overhead panel. The associated valve position indicator
lights and warning lights are located adjacent to the switches.
2 . T_h_e_r_m_a_l_ _A_n_t_i_-_I_c_e_ _(_T_A_I_)_ _V_a_l_v_e_ (Fig. 2 and 3)
A. The TAI valve, located at the 1:30 o'clock position (aft looking forward)
on the fan frame, is line mounted in the TAI ducting and is secured with
V-band couplings. The valve is air operated and is set to regulate
outlet pressure at 50 |3 psi. The valve is fully open at inlet pressures
of 10 to 47 psi. The unit consists of a normally closed butterfly
shutoff valve, a normally open pressure regulator butterfly valve, a
servo pilot valve and associated components which form an insulated air
duct section. If the pressure regulator valve fails to regulate the
pressure, the shutoff valve will maintain the pressure at 75 |10 psi.
B. A manual override provision is incorporated in the valve for direct
mechanical operation and for locking the valve in a partially open
position in the event of system malfunction. The valve is designed to
fail in the closed position. The valve incorporates two position
switches to provide valve position indication in the cockpit.
C. The pressure regulator valve is spring loaded in the valve open
direction. Inlet pressure P1 is admitted through restrictor orifices 1
and 2 to the actuator piston chambers. When the pressures in both
chambers are equal, the actuating mechanism tends to open the valve.
D. The shutoff valve is spring loaded in the valve closed direction.
Downstream pressure P2 is directed through the ground test supply shuttle
valve into both actuator piston chambers. Downstream pressure P2 is also
admitted through a restrictor orifice into the overpressure pilot valve.
The actuating mechanism maintains the valve in the closed position when
the solenoid pilot valve is de-energized.
E. The pressure regulator valve and shutoff valve both have provisions for
manual override by means of external wrenching flats on the valve
position indicators. The pressure regulator may be locked in the open
position by replacing the closed position adjustment setscrew with a
locking screw. The shutoff valve may be locked in either the closed or
midposition by inserting a quick-release pin into the lock hole provided
in the valve cover.
MAINTENANCE MANUAL
F. To lock the pressure regulator valve in the open position, first the
valve clamps must be loosened and the valve hardware must be removed.
Then the valve must be turned until the closed position adjustment
setscrew can be removed and replaced with the locking screw. After the
locking screw is installed, the valve must be aligned and the hardware
and clamps installed.
3 . T_h_e_r_m_a_l_ _A_n_t_i_-_I_c_e_ _(_T_A_I_)_ _P_r_e_s_s_u_r_e_ _S_w_i_t_c_h_
A. The TAI pressure switch senses pressure from a pressure tap in the TAI
ducting downstream of the valve. The function of the switch is to act as
a check on the operation of the valve to prevent overpressurizaton of the
inlet cowl. The switch is set to activate at 65 |3 PSI, and provides
cowl overpressure warning indication by illuminating an amber COWL
ANTI-ICE warning light in the cockpit.
4 . T_h_e_r_m_a_l_ _A_n_t_i_-_I_c_e_ _(_T_A_I_)_ _O_v_e_r_h_e_a_t_ _S_w_i_t_c_h_
A. The TAI overheat switch senses temperature in the TAI ducting downstream
of the valve. The switch is set to activate at 825 |20¡F and will
indicate an overtemperature condition by illuminating the master caution,
anti-ice annunciator lights, and an amber COWL ANTI-ICE warning light in
the cockpit. The unit consists of a thermostatic sensor that actuates a
single-pole, single-throw switch.
5 . O_p_e_r_a_t_i_o_n_ (Fig. 3)
A. Functional Description
(1) When the ENG ANTI-ICE switch is positioned to ON for the selected
engine, 28v dc is supplied to the TAI valve. The valve solenoid is
energized and hot air is directed through the valve to the air
distribution spray ring which contains holes that direct the
anti-icing air to the inner lip of the inlet cowl. The air is
circulated around the inlet cowl and vented overboard through the
TAI exhaust port.
(2) When the ENG ANTI-ICE switch is positioned to OFF, the valve
solenoid is de-energized and the valve closes.
(3) When the ENG ANTI-ICE switch is first positioned to ON, the blue
COWL VALVE OPEN light comes on bright to indicate valve in transit.
When the valve reaches the full open position, the light dims.
(4) When the ENG ANTI-ICE switch is moved to OFF, the blue COWL VALVE
OPEN light comes on bright to indicate valve in transit, then goes
off to indicate valve closed.
(5) When a pressure of 65 |3 psi is sensed by the TAI pressure switch,
the switch is activated causing the amber COWL ANTI-ICE warning
light to come on.
(6) When a temperature of 825 |20¡F is sensed by the TAI overheat
switch, the switch is activated causing the amber COWL ANTI-ICE
warning light to come on.
(7) If the engine is not running and the ENG ANTI-ICE switch is set to
ON, the COWL VALVE OPEN light will come on bright and will stay on.
Under these conditions, if the pneumatic system is pressurized, the COWL VALVE OPEN light may become dim momentarily.
One last note; DC Bus1 for engine 1, DC Bus 2 for engine2.
And hot air is not ingested, it's ducted overboard from the bottom of the cowl lip.
LEM
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I'll have to go back and read my ops manual... bleeds on the 5th and 9th? For some reason that rings no bells.. 8th and 13th, yes.. 5th, 9th.. nope.
Aggh Wileydog3 must be too much time listing to JT8D crackle!
5th and 9th, CFM 56
8th and 13th, JT8D; aggh straight pipes on a frosty morning
From FCOM2 B737-300
5th and 9th, CFM 56
8th and 13th, JT8D; aggh straight pipes on a frosty morning
From FCOM2 B737-300
Engine Bleed System Supply
Engine bleed air is obtained from the 5th and 9th stages of the compressor section.
When 5th stage low pressure bleed air is insufficient for the bleed air system requirements, the high stage valve modulates open to maintain adequate bleed air pressure. During takeoff, climb, and most cruise conditions, low pressure bleed air from the 5th stage is adequate and the high stage valve remains closed.
Engine Bleed Air Valves
The engine bleed air valve acts as a pressure regulator and shutoff valve. With the engine bleed air switch ON, the valve is DC activated and pressure operated. The valve maintains proper system operating pressure and reduces bleed air outflow in response to high bleed air temperature.
Engine bleed air is obtained from the 5th and 9th stages of the compressor section.
When 5th stage low pressure bleed air is insufficient for the bleed air system requirements, the high stage valve modulates open to maintain adequate bleed air pressure. During takeoff, climb, and most cruise conditions, low pressure bleed air from the 5th stage is adequate and the high stage valve remains closed.
Engine Bleed Air Valves
The engine bleed air valve acts as a pressure regulator and shutoff valve. With the engine bleed air switch ON, the valve is DC activated and pressure operated. The valve maintains proper system operating pressure and reduces bleed air outflow in response to high bleed air temperature.
Last edited by c100driver; 18th Jan 2007 at 19:35. Reason: clarity
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I did spent quite a bit of time with the JT8D and probably shut down more JT8Ds than any other engine. Was on the 737 and 727.. as well as in the -200 series engine, on the MD-80.
When I first got on the CFM airplanes, I was surprised at a number of things including how quiet the engine wa, how SLOW the spool time was and how far back the throttles were when established on final. Also, initially, without the JT8D whine, it took a while to retune my ear for the right engine pitch with the correct amount of thrust on final.
I enjoyed the -200 but the -300/400 were not my favorites. Too small a cockpit with too much fuel and too slow. 5hrs at .74 was tough.
Kelleher was brilliant in getting Boeing to build him a baby-757 with the new gen 737s. New wing. More thrust. Higher altitude and higher cruise speed... So SW essentially got a downsized 757 without the problems associated with introducing a different aircraft.
Quite interesting looking at the initial 737-100 of which very few were built and the latest, the 737-900.. and all done with just difference training. Right.....
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Now, about your spelling.... and 'thrust you'? Pun or error?
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Understood. The 'next' was an attempt at humor which apparently failed. I knew the post was correct for the -200 as I was reading from the manual as I typed the explanation.
Glad to know it was just a mis-type on your part. Don't want to think you're a 'looser'. But then I should have recognized that by your forum name.
Glad to know it was just a mis-type on your part. Don't want to think you're a 'looser'. But then I should have recognized that by your forum name.
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Thanks everyone, I am pretty sure I now understand the 'pneumatic' portion of the operation of this valve( and probably other 'electric pneumatic' valves). It appears that the valve itself utilizes the stream of air that that is being controlled, to open/close the valve. In this case, compressor bleed air. I had wondered about this, as I thought there may have been an independent/separate source of air, which would lead me to think that should that source not be available, the valve would not open/close.GOT IT!!thanks
