Author Topic: Overspeed warning?  (Read 1446 times)

Daniel Vieth

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Overspeed warning?
« on: July 22, 2010, 01:00:47 AM »
I have a 1963 p-35 and was making my decent under class c to get to my destination last evening and what sounded like the stall warning came on.  I checked airspeed and it indicated 160 mph.  I felt a slight shimmy in the front of the plane and pulled out of the decent.  Is there a chance that what i heard was an overspeed warning and small vibrations because of it?  Could my airspeed indicator have malfunctioned?   anyone heard of this.  The planes airspeed has read correct since then and everything was fine after that but it did make me think a bit.  The vibration only lasted about 2 seconds until I pulled out of the decent and then the warning came off.   

Daniel Vieth

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Overspeed warning?
« Reply #1 on: July 22, 2010, 07:24:35 AM »
Update:  found that I may have been loaded aft of cg.  weight and balance should all have been fine but my 240 pound friend without my knowledge had moved his seat in the back all the way aft.  Almost 6 inches.   This could have been a factor and what I may have been experiencing was actually a stall?   Hmmmm.   I will be adding "don't move your seat" to my passenger briefing.   

Gary Hines

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Overspeed warning?
« Reply #2 on: July 24, 2010, 10:45:09 AM »
Daniel,

There are a lot of guys around here that are a lot more knowledgeable than myself, but after flying Bonanzas for many years and maybe a few times with aft, I don't think cg had anything to do with it.  Sounds possibly like a mild flutter, from what, I don't have a clue.  Maybe the experts will chime in if they didn't all head out to Osh.

Gary

Daniel Vieth

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Overspeed warning?
« Reply #3 on: July 28, 2010, 09:33:46 AM »
I'm hopefully going up soon with another Bonanza owner this weekend or next week sometime and am going to ask him.  I realized that I was at idle during the decent and I know in the arrow there was a landing gear up warning.  Does the Bonanza have an Idle gear up warning?  The vibration was nothing... I think I was just over thinking the decent.  But I did hear the stall like warning sign the other day when I was descending at idle.  Gear up warning?   hmmm.

Tracy Ryan

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Overspeed warning?
« Reply #4 on: July 28, 2010, 10:09:46 AM »
Ok, please don't take this question the wrong way, but how long has it been since you've read your POH front to back ? I encourage everyone to read it at least once a year.

There are two warning horns in your aircraft.

The stall warning horn is a solid tone and is self explanitory as to why it makes noise.



The throttle warning horn is an intermittent tone and will be activated when the throttle is retarded to a manifild pressure at or below 12 inches and the landing gear is in any position other than down. The 12" setting is achieved by the adjustment of a microswitch attached to the throttle cable housing in the engine compartment.

Both of these safety horns are described in the POH.

Daniel Vieth

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Overspeed warning?
« Reply #5 on: July 28, 2010, 11:19:38 AM »
I read it front to back about 3 weeks ago.  Also read the original from 1963, but that didn't have much info in it.   I'll look a little closer.  Thanks for the info.

Tracy Ryan

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Overspeed warning?
« Reply #6 on: July 28, 2010, 12:20:22 PM »
It sounds like you have the thinner Owners Manual and not the POH/AFM. The Owners Manual is very sparse on systems details. The POH/AFM for the N and P models is Beech part number 35-590094-7 and can be ordered from Beech direct online, or you can go through any Beech dealer. It's $80 and there's no need to buy the revision service. The last revision was way back in 1976.


Jimmy Borger

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Overspeed warning?
« Reply #7 on: July 29, 2010, 04:38:18 AM »
I don't know if the gear warning horn works the same on your plane as it does on mine but a few years back I took my F-35 to a different shop than I normally use for an annual.  Afterwards I made a test hop to make sure everything worked.  When I reduced the throttle to start down I was startled by a loud, steady horn.  I found that as long as the throttle was above 17 inches MP the horn stayed off.  I slowed down, dropped the gear, and reduced the throttle to the normal 15 inches I use for landing and the horn stayed off.

The shop owner explained that the gear warning throttle position had been set wrong and he had reset it to Beech specs during the annual.

Tracy Ryan

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Overspeed warning?
« Reply #8 on: July 29, 2010, 05:53:16 AM »
Here is the excerpt from the 35 Shop Manual. I think maybe that shop needs to buy one. Every owner should have an IPC and Shop Manual. The range is 12 to 14 inches manifold pressure, but 12 is best so you can better control descents without the horn blaring at you.


Daniel Vieth

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Overspeed warning?
« Reply #9 on: July 29, 2010, 05:54:45 AM »
Mine definitely sounded like a long steaky horn.  Almost like a stall warning.  I'm going to double check my poh when I go out to the hangar next.  When I was doing my quicker than normal decent I believe my mp was somewhere lower then 15 or close to it.  If I have the manifold pressure above that it does not go off.  Going to verify this next time I go up.

Tracy Ryan

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Overspeed warning?
« Reply #10 on: July 29, 2010, 06:26:36 AM »
Turn on your battery and go hold the stall vane up to turn it on. Do you get a solid or intermittent horn ? If both horns are solid, then I would suspect that someone in the past replaced the throttle/gear horn for some reason and installed the wrong item.

Gary D'Antoni

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Overspeed warning?
« Reply #11 on: August 08, 2010, 04:44:18 AM »
Hi Daniel,

There is no "Overspeed" warning on the P-Model (P-35) Bonanza.  Any warning would be characterized by the sights and sounds from your pilot's seat as compared to those sights and sound during your bird's normal operation.   But, don't disregard these.   You are doing the right thing by investigating these.

I happen to own a rare copy of the original 1961 publication of the P-35 Model Owner's Manual.  The information contained within is quite a difference from the information contained in the current publication.   That said, there are two audible warnings (other than the Angle of Attach, or Stall warning).   These  are:

      1.  The aforementioned throttle setting at approximately 12" MP with gear up and locked.

      2). Gear switch engerized to the "Up" position with the gear safety switch (squat switch) open (requiring gear struts to be depressed).

The only possibilities that the first was causal is that the proximity switch has moved (on the throttle shaft).   Not likely but, worth having checked by your AI.  Or, your throttle position was at or near the setting commensurate with 12" MP thereby energizing the proximty switch.

Although, neither of these were likely characteristic of the circumstances during your high speed descent.  They are worth having your AI investigate.   

However, once yoiu eliminate these two as sources of warnings, let's now look at the stall horn warning as a possible source of audible warning.   We should be clear that there is no relationship between the stall warning system and the airspeed indicator/system.   The stall warning is simply an indicator of your bird's approaching its critical angle of attack.  This is that mechanical switch located near the leading edge of your left wing.  Energizing this switch would not be likely in the high speed descent that you descibed (which is really not high speed circumstance and well within the normal operating speed range).  

If the circumstances were as you described, I would look for sources of audible sound other than these warnings.   Perhaps perhaps even a gear door being slightly open causing the audible sound similar to that which you described.  I would recommend that you have a recommended Beech AI look at your landing gear system (or better yet, attend the ABS service clinic).  The landing gear is one of the systems on which they focus a fair amount of time and attention.  If convinced that this is not the source, have your AI look for other sources of sound generators similar to the landing gear system.  The landing gear system's geometry and tensions are checked out (measured) thoroughly.

  Of course the by-product of attending the ABS Service Clinic is that the attending AI can recommend other possible sources of sound which you descibe to him.  These clinics are intended to be very interactive so that you, the owner operator, can better understand the mechanical health of your airplane while appreciating the requirement for regular scheduled maintenance.       

 

In my humble opinion, neither the stall warning system nor your gear warning system seem to be the logical sources.

All the best.