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Landing Gear Retracts With WOW.


Bulldog_1
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Instant mission "Take Off": Landing Gear retracts with weight on wheels at zero knots when landing gear lever is inadvertently left in the up position. Aircraft is code 3 and impounded pending investigation.

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IRL Retired Maintainer of the AT-38B: F-4E/G: F-15A/B/C/D: and McDonnell Douglas/Boeing Technical Advisor for the F-15C/D. I drive trains now. :yawn:

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Does the F-5 has a WOW switch? For comparison: on the F-16 (IIRC) the wow switches do not prevent the LG to go up, the prevent the handle for being raise. So if the LG handle was left up, the LG will go up regardless of WOW switches.

http://www.f-16.net/g3/f-16-photos/album30/aec

Undercarrage retracted while parked. Gear pins were pulled during an ops check.

Edited by mvsgas

To whom it may concern,

I am an idiot, unfortunately for the world, I have a internet connection and a fondness for beer....apologies for that.

Thank you for you patience.

 

 

Many people don't want the truth, they want constant reassurance that whatever misconception/fallacies they believe in are true..

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WOW Switch

Inkedf-5a-strbrd-main-landing-gear-2_LI.jpg.975901923377885b18aec90858eb664c.jpg

Digital Storm Lynx: i9-10850k (5.2 GHz): 64GB RAM (3200 MHz): 2TB SSD M.2 Samsung 970 EVO: 2TB Samsung HD: GEFORCE 2080 TI: Thrust Master WartHog (modified): TM F-18C joystick: Saitek Rudder Pedals: HP Reverb PRO: Volair Sim Cockpit: Current Stable Version of DCS :thumbup:

IRL Retired Maintainer of the AT-38B: F-4E/G: F-15A/B/C/D: and McDonnell Douglas/Boeing Technical Advisor for the F-15C/D. I drive trains now. :yawn:

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...when landing gear lever is inadvertently left in the up position.

Ok, but does it prevent the handle to go up or the landing gear itself?


Edited by mvsgas

To whom it may concern,

I am an idiot, unfortunately for the world, I have a internet connection and a fondness for beer....apologies for that.

Thank you for you patience.

 

 

Many people don't want the truth, they want constant reassurance that whatever misconception/fallacies they believe in are true..

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Ok, but does it prevent the handle to go up or the landing gear itself?

 

No, it does not prevent the "Gear Handle" from being moved to the up position, however, The WOW or Squat Switch is mounted on the gear by two attach points – one on each side of the two telescoping parts of the gear, allowing the switch to be electrically closed or open, depending on if the gear is compressed or extended (weight on/weight off).

When the aircraft is in the air the telescoping part of the landing gear is fully extended mostly by the pressure of the gas inside it. In this extended position the Squat Switch is held in the electrically closed position, allowing the gear to be operated up and down.

When the aircraft is on the ground the landing gear is compressed by the weight of the aircraft upon it. In this compressed position the Squat Switch is held in the electrically open position, preventing the gear from being operated up or down.

 

In addition, the F-16 does have WOW proximity switches, that particular incident you referred to was due to an electrical malfunction and an unqualified individual.

Digital Storm Lynx: i9-10850k (5.2 GHz): 64GB RAM (3200 MHz): 2TB SSD M.2 Samsung 970 EVO: 2TB Samsung HD: GEFORCE 2080 TI: Thrust Master WartHog (modified): TM F-18C joystick: Saitek Rudder Pedals: HP Reverb PRO: Volair Sim Cockpit: Current Stable Version of DCS :thumbup:

IRL Retired Maintainer of the AT-38B: F-4E/G: F-15A/B/C/D: and McDonnell Douglas/Boeing Technical Advisor for the F-15C/D. I drive trains now. :yawn:

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... it does not prevent the "Gear Handle" from being moved to the up position...

 

Actually that is exactly what it should do. When on the ground, the gear lever is locked down by a solenoid. Check page 1-69 of the TO 1F-5E-1 "LANDING GEAR DOWNLOCK OVERRIDE"

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I don't teach Aircraft Maintenance anymore, nor am I an Aircraft Maintenance Advisor for Boeing anymore, I drive trains now and I really don't have time to instruct.

 

The purpose of this thread was to report to the developers that the landing gear retracted while the aircraft was on the ground, not supposed to happen.

 

Thank you.

Digital Storm Lynx: i9-10850k (5.2 GHz): 64GB RAM (3200 MHz): 2TB SSD M.2 Samsung 970 EVO: 2TB Samsung HD: GEFORCE 2080 TI: Thrust Master WartHog (modified): TM F-18C joystick: Saitek Rudder Pedals: HP Reverb PRO: Volair Sim Cockpit: Current Stable Version of DCS :thumbup:

IRL Retired Maintainer of the AT-38B: F-4E/G: F-15A/B/C/D: and McDonnell Douglas/Boeing Technical Advisor for the F-15C/D. I drive trains now. :yawn:

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No, it does not prevent the "Gear Handle" from being moved to the up position, however, The WOW or Squat Switch is mounted on the gear by two attach points – one on each side of the two telescoping parts of the gear, allowing the switch to be electrically closed or open, depending on if the gear is compressed or extended (weight on/weight off).

When the aircraft is in the air the telescoping part of the landing gear is fully extended mostly by the pressure of the gas inside it. In this extended position the Squat Switch is held in the electrically closed position, allowing the gear to be operated up and down.

When the aircraft is on the ground the landing gear is compressed by the weight of the aircraft upon it. In this compressed position the Squat Switch is held in the electrically open position, preventing the gear from being operated up or down.

 

In addition, the F-16 does have WOW proximity switches, that particular incident you referred to was due to an electrical malfunction and an unqualified individual.

 

I don't teach Aircraft Maintenance anymore, nor am I an Aircraft Maintenance Advisor for Boeing anymore, I drive trains now and I really don't have time to instruct.

 

The purpose of this thread was to report to the developers that the landing gear retracted while the aircraft was on the ground, not supposed to happen.

 

Thank you.

All that and you still did not answer the question. You formerly working at Boeing or being an instructor in the past has no bearing on the subject.

The F-16 incident happened during a brakes ops check, there was no electrical malfunction and F-16 do not have proximity switches for the WOW.

The point of mentioning the F-16 was that wow switches are used differently on the different aircraft. If you have technical data, saying why landing gear should not go up on the ground, just provided. If developer agree it will be change. No need to talk down to dolfo and saying: "is wrong cause I say so" is not the best argument.

 

Oh well, if the F-5 changes in DCS I guess you where right. Moving on.


Edited by mvsgas

To whom it may concern,

I am an idiot, unfortunately for the world, I have a internet connection and a fondness for beer....apologies for that.

Thank you for you patience.

 

 

Many people don't want the truth, they want constant reassurance that whatever misconception/fallacies they believe in are true..

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TO 1F-5A-1 has a better description of the landing gear lever.

 

Page 1-34

 

"...and can be moved from LG DOWN to LG UP position only when dc bus power is available under the following conditions: landing gear struts fully extended or the landing gear lever downlock override button is pressed and held. When the weight of the aircraft is on the struts and the lever is in the down position, a locking solenoid is deenergized, preventing the lever from being moved from LG DOWN position. ..."

 

So according to the TO the weight on the struts does prevent the gear handle from being moved from LG DOWN, it seems.

 

If moving the gear lever to LG UP while on the ground should retract the landing gear is another story. I do not see what the fuss is all about.

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Not sure if it makes much sense to compare the A with the E as there were a lot of changes between these two and more than 10 years experience with the A had passed when the E was introduced.

 

Agreed. Lots of differences. But the rest of this system is described in the same way, allowing to interpret as a simplification of the manual. The gear downlock override is still there, described in the same manner. Serves the same purpose. Just take the time to read the TOs if you wish to compare. Pretty common feature, many airplanes had/have it. Even Boeing's products.

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TO 1F-5A-1 has a better description of the landing gear lever.

 

Page 1-34

 

"...and can be moved from LG DOWN to LG UP position only when dc bus power is available under the following conditions: landing gear struts fully extended or the landing gear lever downlock override button is pressed and held. When the weight of the aircraft is on the struts and the lever is in the down position, a locking solenoid is deenergized, preventing the lever from being moved from LG DOWN position. ..."

 

So according to the TO the weight on the struts does prevent the gear handle from being moved from LG DOWN, it seems.

 

If moving the gear lever to LG UP while on the ground should retract the landing gear is another story. I do not see what the fuss is all about.

 

I agree. Thank you. :thumbup:

Digital Storm Lynx: i9-10850k (5.2 GHz): 64GB RAM (3200 MHz): 2TB SSD M.2 Samsung 970 EVO: 2TB Samsung HD: GEFORCE 2080 TI: Thrust Master WartHog (modified): TM F-18C joystick: Saitek Rudder Pedals: HP Reverb PRO: Volair Sim Cockpit: Current Stable Version of DCS :thumbup:

IRL Retired Maintainer of the AT-38B: F-4E/G: F-15A/B/C/D: and McDonnell Douglas/Boeing Technical Advisor for the F-15C/D. I drive trains now. :yawn:

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Did some experimenting (NTTR):

 

1. Cold aircraft (no electrical power, engines not running): Gear handle can be moved from LG DOWN to LG UP. Gear lever should not move. The de-energised state of the locking solenoid is "locked".

 

2. With either battery or ground power ON: Gear handle only moves from LG DOWN position if DOWNLOCK OVERRIDE button is pressed and held. Doing so does not retract or collapse the landing gear. This behaviour seems correct. The landing gears are locked in the down position by the spring-loaded, overcenter downlocks, and if the airplane is at rest and remains undisturbed the landing gears should not collapse.

 

3. With presence of Hydraulic Power (even just motoring the engine with the ground air supply built enough hydraulic pressure in this test) and gear lever in the LG UP position (through use of DOWNLOCK OVERRIDE) landing gear eventually tries to retract and collapses. There is a caution on -1 p1-69 "with utility hydraulic pressure available, landing gear safety pins must be installed before using the reset control to prevent possible gear collapse." Now this note refers to the Gear Alternate Release Reset Control, not the downlock override, but it may be correct that the landing gear collapses in this scenario.

 

 

EDIT:

 

4. In some missions the airplane starts above the surface and is dropped from a few cm on to the tarmac. If gear is unlocked or commanded up before touching the ground I think it is not unreasonable to have it collapse. More a DCS feature than incorrect system modelling. Still would like to see point 1. looked into.

 

-dolfo


Edited by dolfo
added comment 4.
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