Service Bulletin M20-209

[Cyril Gibb]

I read this SB from a pointer on another thread.  It increases the VLe on early 201s from 120 mph to 150 mph with just a change in placards, no mechanical changes.

I have a 75F with the low VLe.  Are there differences in the gear mechanism between the mid 70s M20Fs and 201s?  I'd love to be able to drop the gear without slowing to a walk on an approach with a commercial jet on my tail.

If the mechanical ratios, hence loads, are the same it might be worth approaching Mooney.

[Bob_Belville]

I have a M20E and the landing gear speed is a painful 120 MPH. But i am pretty sure a J has a higher speed for extension and Vle and Vlo (gear extension) of 150 MPH - 130 knots. Apparently the Vlo (gear retraction) was kept at 120 mph. 

This makes sense, it is much more difficult to raise my manual gear as speed increases.  

See figure 2-1, page 33:  http://www.zitair.aviators.net/Pilots Operating Handbook G-BJHB.pdf 

 

[Marauder]

11 hours ago, Cyril Gibb said:

I read this SB from a pointer on another thread.  It increases the VLe on early 201s from 120 mph to 150 mph with just a change in placards, no mechanical changes.

I have a 75F with the low VLe.  Are there differences in the gear mechanism between the mid 70s M20Fs and 201s?  I'd love to be able to drop the gear without slowing to a walk on an approach with a commercial jet on my tail.

If the mechanical ratios, hence loads, are the same it might be worth approaching Mooney.

Cyril -- I think the difference is the gear ratio that the motor operates at. Our 75's run at somewhere around 20:1 and the Js at 40:1. I am going to check with a MSC. I would love the higher gear speed as well. It is weird the flaps can be deployed at a higher speed than the gear. The other option is installing speed brakes. I think Bob has those. I have a few times where they could have come in handy.

[Cyril Gibb]

2 hours ago, Bob_Belville said:

I have a M20E and the landing gear speed is a painful 120 MPH. But i am pretty sure a J has a higher speed for extension and Vle and Vlo (gear extension) of 150 MPH - 130 knots. Apparently the Vlo (gear retraction) was kept at 120 mph. 

 

The SB applies to M20Js from ser# 24-0002 to 24-0377 that had a Vle of 120.  Seems like Mooney just used the M20F numbers initially for gear extension and then (via SB) allowed the early models to use the higher speed without changing anything mechanical.

So back to the question: is there any difference between the later M20F gear mechanism and the initial M20J gear mechanism?  If they are identical, it would seem that 150 Vle would be O.K. for my M20F (but NOT legal without an equivalent SB from Mooney).

If the gear is identical, perhaps it would be an opportunity for Lasar or someone to get an STC using equivalence criteria.

[Cyril Gibb]

Just now, Marauder said:

Cyril -- I think the difference is the gear ratio that the motor operates at. Our 75's run at somewhere around 20:1 and the Js at 40:1. I am going to check with a MSC. I would love the higher gear speed as well. It is weird the flaps can be deployed at a higher speed than the gear. The other option is installing speed brakes. I think Bob has those. I have a few times where they could have come in handy.

I thought about that. I have the retrofitted 40:1 gears.

[Marauder]

Just now, Cyril Gibb said:

The SB applies to M20Js from ser# 24-0002 to 24-0377 that had a Vle of 120.  Seems like Mooney just used the M20F numbers initially for gear extension and then (via SB) allowed the early models to use the higher speed without changing anything mechanical.

So back to the question: is there any difference between the later M20F gear mechanism and the initial M20J gear mechanism?  If they are identical, it would seem that 150 Vle would be O.K. for my M20F (but NOT legal without an equivalent SB from Mooney).

If the gear is identical, perhaps it would be an opportunity for Lasar or someone to get an STC using equivalence criteria.

I think there are two threads you asked this. Either that or I am losing my marbles. I think the difference is the gear ratios. I believe the Dukes were on the early Js. Mine has an ITT but I think they were considered interchangeable. Not sure if the inner gear door plays a role as well.

[Marauder]

Just now, Cyril Gibb said:

I thought about that. I have the retrofitted 40:1 gears.

Worthwhile asking a MSC or Mooney.

[Marauder]

Just now, Marauder said:

I think there are two threads you asked this. Either that or I am losing my marbles. I think the difference is the gear ratios. I believe the Dukes were on the early Js. Mine has an ITT but I think they were considered interchangeable. Not sure if the inner gear door plays a role as well.

I am losing my marbles. Same thread!

[Mooneymite]

Just a thought:  regardless of "legal extension speed", the higher the speed at which the gear is operated, the more stress on the gear components.  While I have a 120 retraction/extension limit, I've always tried to operate the gear well below that limit.  Obviously, if you need it down NOW, use it!

Edited May 31, 2016 by Mooneymite

[Marauder]

Just a thought:  regardless of "legal extension speed", the higher the speed at which the gear is operated, the more stress on the gear components.  While I have a 120 kt. retraction/extension limit, I've always tried to operate the gear well below that limit.  Obviously, if you need it down NOW, use it!

Gus - I often thought about that as well. From what I can tell, our 75s have the same gear as the 77s. Just curious what makes one legal to go higher the other not.

BTW -- I hope you meant 120 MPH not KTS. I thought you are limited to the same 104 KTS as me.

Sent from my SM-G900V using Tapatalk

[Mooneymite]

Yes.....MPH CAS.  Sorry.  You are correct.

As you know, I have to check the gear lash each two hundred hours.  In the years I've been doing the AD, I haven't had noticeable increase in the amount of lash.  I don't know if that's because the AD is bogus, or it is due to the conservative manner of operation.  In any case, retracting and extending at lower airspeeds makes ME feel better.  Who knows if it makes any real difference?  

I also try not to extend flaps at limit speeds for the same reason.

Isn't it interesting how working on your own plane (under supervision, of course) makes one operate more carefullly?

Edited May 31, 2016 by Mooneymite

[mike20papa]

20 inches...!  Cruise descent in my A model is 16 inches, keep the same mixture at cruise power till you approach pattern alt.  Set the trim up for 500fpm descent and earn back all of that climb energy.  Now I know flying in Texas is not like the UK, but coming down thru the condensation level I 'm primarily worried about the yellow arc, then gear extension is never a problem.  Also, if you're having problems reaching gear extension speed, trim settings for a descent landing are never going to be achieved.  If your fast & high on approaching the pattern, pull the power off, pull the nose up like you mean it, roll the airplane into a steep turn and lay off the elevator.  Do it left then right and level off when you get to pattern altitude & 120 mph.. By the way, I'm usually around 12 in at pattern...20 inches and I would be in the next county! I religiously use 100mph gear extension in my A model, and it's never a problem getting to it.

I tell other pilots that the most difficult thing about flying a mooney can be to simply get it to quit flying!

[mooniac15u]

17 hours ago, mike20papa said:

20 inches...!  Cruise descent in my A model is 16 inches, keep the same mixture at cruise power till you approach pattern alt.  Set the trim up for 500fpm descent and earn back all of that climb energy.  Now I know flying in Texas is not like the UK, but coming down thru the condensation level I 'm primarily worried about the yellow arc, then gear extension is never a problem.  Also, if you're having problems reaching gear extension speed, trim settings for a descent landing are never going to be achieved.  If your fast & high on approaching the pattern, pull the power off, pull the nose up like you mean it, roll the airplane into a steep turn and lay off the elevator.  Do it left then right and level off when you get to pattern altitude & 120 mph.. By the way, I'm usually around 12 in at pattern...20 inches and I would be in the next county! I religiously use 100mph gear extension in my A model, and it's never a problem getting to it.

I tell other pilots that the most difficult thing about flying a mooney can be to simply get it to quit flying!

Vno is significantly higher for a J. You can hold a lot more speed in the descent without hitting the yellow arc. 

[jetdriven]

19 hours ago, Hyett6420 said:

I have a later J and it is 130 knots, and it takes an age to slow down to that speed.  I still have not found a "brake" method that would not damage the engine, ie  dumping the cowl flaps for instance.  I have just got into the habit of pulling the power back to 20 inches and dial the prop back to 21.  After about 5-10 miles i can drop the gear.  

 

I've had a 196 knot ground speed on downwind more than once, and I didn't have to beat up the plane to land it either. It only takes two miles to slow down from that speed to ~110 kt when the power is set to 20", then lowered to 17".   The big thing is hold it level so it can slow down. You can't go down and slow down both at the same time like you used to could in a Cessna. 

Edited June 1, 2016 by jetdriven

[Ron McBride]

69F  Dukes gear box.  20:1 gears, 120 MPH gear speed.   Gears were worn out at aver 4000 hrs.   I had 40:1 installed, gear speeds still the same.  Could be higher, maybe in the early J's.   40:1 gears are much smoother to operate.   Twice as long for the same motion.

Ron

[N201MKTurbo]

A rudder to the floor forward slip will slow it down almost instantly.

If you explain it to your passengers before you do it they don't freak out too badly.

Edited June 1, 2016 by N201MKTurbo

[N201MKTurbo]

3 minutes ago, Hyett6420 said:

A what and how?  

https://en.wikipedia.org/wiki/Slip_(aerodynamics)

Push one of the rudder peddles to the floor and bank to maintain track. The plane will be flying sideways through the air and it creates a huge amount of drag. The plane will slow down from cruise to landing speed in about 10 sec.

Edited June 1, 2016 by N201MKTurbo

[Bob_Belville]

35 minutes ago, Hyett6420 said:

A what and how?  

I feel certain a "Slip" was part of your primary training. Perhaps by a different name in the UK?

[Guest]

My 400HP brand P will cruise at 220 indicated and has a 150 gear speed.  I lose that speed with planning and don't have to resort to any unusual flying.

Clarence

[Mooneymite]

15 minutes ago, M20Doc said:

 I lose that speed with planning.....

Speed brakes and high landing gear extension speeds are for "instant gratification"!  

[carusoam]

'Hit the brakes, Mav...' - Goose(?)

1) speed brakes deployed.

2) power off, high rpm.

3) gear down (gear speed for the LB is 140kias (?))

4) descend at gear speed (legs extended) or slow down quickly at a level attitude...

5) slowing the '65 M20C, turning it sideways to the wind using max rudder is pretty effective.

Use POH procedures and smoothness when adding and removing these inputs...

Some of these are more obvious than others.  I found the braking effect of increasing prop rpm most interesting.  I didn't expect it to be as strong as it is.   Similar to downshifting to slow down the firebird without hitting the brakes...

I am still only a PP.  Not a CFI.

Best regards,

-a-

[Marauder]

My 400HP brand P will cruise at 220 indicated and has a 150 gear speed.  I lose that speed with planning and don't have to resort to any unusual flying.

Clarence

Of course you don't need to resort to unusual flying. Pull those 400 horses off and that Piper airframe will slow down like maple syrup in January in Ontario.

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[Bob_Belville]

4 minutes ago, Hyett6420 said:

Nope, never did one.  N210MKTurbo just explained it and i was taught it afterwards as a way of showing passengers somehting out of the window, never as a slip   

What did you train it? As I recall a C150 loves to "slip". But it's been over 45 years since I've flown one and my memory is suspect.