252 versus 261 Thunderbird Turbo Conversion by Mod Squad

[Jsavage3]

I've decided to get a turbo and any information regarding the differences between a stock 252 and the 261 Thunderbird Turbo Conversion by the Mod Squad would be most welcome.

Any differences in useful load?  Performance?  Anticipated maintenance?  Parts availability?  Same turbo or waste-gate?  Ease of operation?

Age seems to always be a player...i.e. a modified 231 from the early 1980s versus a 1986-1989 252.

Any information from a previous or current owner would be much appreciated.

Thank you and Happy New Year!

[Bennett]

The 261 and 262 conversions are essentially the same. Mod Works vs Mod Squad. Coy Jacobs vs Tim Combs. I had a 261 for about 18 years. The POH for the 261 was (so far as I know) a reprint of the 252 POH, except all references to 24 Volts. The 261 retained the 231 12 Volt electrical system ( mine had two alternators, and the 231 square windows). It was a great airplane, and at the time of conversion, far less expensive than the then new 252s.

[Mcstealth]

The door to door time difference between the two machines Would be negligible. Both haul ass.

There is a nice looking 262 listed on this forum.

a 252 can be upgraded to an Encoure for many AMU's, a 231 can not (as taught to me by KSMooniac).

The 252 has the least useful load in the fleet. 

They both have the auto waste gates and MB engines believe. 

If you really want the "better" performance and UL, step up to the Encore if budget allows.

DF 

Edited January 1, 2016 by Mcstealth
Added credit to Mooniac

[anthonydesmet]

I currently own a 262 and couldn't be happier. As Bennett stated, the POH is basically the 252 for engine parameters. As already stated if you go with an earlier 261/262 you might miss some of the finer cabin features that your used to with the 86 J. Like the split back seats, nice white panel and adjustable pilot/copilot seats.  But whatever you decide you are going to LOVE being able to cruise in the mid-high teens (especially in the summer), nice smooth cool air at 170+knots.  Plus really take advantage of some the higher altitude tail winds. I am pretty sure speed brakes were standard for both mods and most likely on the 252 but just verify because you will definitely want them when you go turbo.

[Steve Dietrich]

Somewhat "me too" reply -  I did a Mod Works conversion to my 231  and flew it for about 1,000 hours (3,800 total) 

I posted a longer note to the flight test comment earlier 

If it is not dual alternator I would plan on investing in led lighting and also replace the battery at the first sign of weakness

 

Respectfully disagree on speed brakes being essential.  you do need to do careful planning .    Cruise descent 6-9 NM  per 1,000 feet .  You are using the energy to push the airplane rather than creating turbulence with the spoilers . You need to be assertive with Center   on getting your descent started when needed.  Speed brakes are nice but far from essential  

 

[M20F]

8 minutes ago, Steve Dietrich said:

Respectfully disagree on speed brakes being essential.  you do need to do careful planning .    Cruise descent 6-9 NM  per 1,000 feet .  You are using the energy to push the airplane rather than creating turbulence with the spoilers . You need to be assertive with Center   on getting your descent started when needed.  Speed brakes are nice but far from essential  

My take is more from a safety point of view which is if your O2 goes out at 250 or you catch on fire, it would really be nice to be going down fast.  I don't have speed brakes in my F/Rayjay setup but when I drop in long range tanks the brakes are coming with them.  I also go in/out of ORD Class B (MDW C if you are coming from E/S as well) and you can be as assertive as you want with them but you are either getting low a lot sooner then you want, slam dunking it, or over flying the B and looping to land.  Speed brakes would fix that problem.

[Steve Dietrich]

Some very good points .  I'm a firm believer that a second O2 source is essential for the pilot above Fl 180  and prudent at even lower altitudes 

 

 

 

[carusoam]

Steve,

Do you go as far as running two O2 systems at the same time or just a back-up ready to go?

With the small number of planes that have had run into O2 issues at high altitudes, I would be interested in info regarding a dual system where both are continuously running or some impressive automation that starts the back-up.

The old systems just don't do what they should that far up.

Best regards,

-a- 

[kortopates]

There is nothing unreliable about our built-in 02 systems in the Mooney. Its dirt simple and that is big factor in its reliability. That said I share Steve's opinion on a backup (and on speed brakes since I hardly ever use mine since learning to master my descent planning and not be shy with controllers but that's another story - although I do agree we can't get down fast enough if on fire). 

Rather than complicating things I use this simple and affordable device as a backup: http://www.mhoxygen.com/index.php/portable-constant-flow/emergency-systems/165-ntg-co-pilot-portable-o2-copilot It essentially guarantees the backup tank won't be empty since its sealed till usage and will provide plenty of O2 to get me down without being rushed.

With many years flying on O2, which is what turbo flying is all about,  I have seen many so called  "failures", but non were even close to an emergency. The most common is pilot induced from not having the scott connector all the way locked into the fitting which prevents O2 from flowing. But that's pretty obvious with our flow meters and Pulse oximetry, and quick reach back to the back seat to fix it and Iam back to being good (I mostly fly in the right set where the O2 port is out of sight), in the pilot seat its even more obvious. But I suspect this is the sort of failure that has claimed some pilots flying high alone. The other thing I've seen happen is the hose pop off the scott fitting. I've had to fly once while holding it on till I got lower.  I could have used the backup but holding it seemed easy since it didn't take more than light pressure to hold on. So what could go wrong to create a real emergency? Personally I think its much more likely when you add on these new high tech gadgets to save your O2 - now your failure modes can really grow - just loose electrical power for starters.  But why do we need to save O2 with 115' cu/ft builtin tank?  Last month we flew from San Diego to Cuba and back and still had plenty of O2 left when we returned. We've also flown to CENAM and back with one refill in CENAM just to make sure we had plenty. At home I fill it myself with a 2 tank cascading system - it keeps my O2 refills very cheap!. 

I used to worry that maybe my regulator could fail and block O2 but I am still waiting to read about the first such occurrence reported by the NTSB. As far as I know that's not a failure mode. I know my O2 system really well and know that a leak is not going to drain my tank in front of my eyes. Even a high pressure leak will take over an hour and a low pressure leak will take days. Only a ruptured low pressure line is going to prevent the flow of O2 to the cabin ports. The real emergency in my mind is a failure of the gauge indicating pressure when its actually empty and that may be another nearly impossible failure mode.

Still though I don't want to bet my life on something I may not have thought up yet. Plus the added insurance and peace of mind of backup is so easy to carry and such cheap insurance I consider it mandatory, so I carry the above backup which fits in the seat back - even though I think the odds of needing it are infinitesimally small. I know many are very concerned about having only seconds of useful consciousness after reviewing TUC tables and being told they were based on young cadets and the average geriatric pilot won't last near that time. If you're really concerned you really need to take the chamber ride and learn the truth for you at 24-25K'. You'll be pleasantly surprised and will probably see all your fellow geriatric pilots exceed the tables easily. But more importantly, hopefully you'll leave with an understanding of your own symptoms so you can readily recognize yourself becoming hypoxic. If not and if your one of those people that doesn't recognize themselves becoming hypoxic I hope you set a maximum ceilings accordingly not to fly above it and in the flight levels without another person or pilot on board that can recognize it and alert you.

Sorry to get a bit off topic....

Edited February 10, 2016 by kortopates

[N201MKTurbo]

I have an emergency oxygen system from a Malabu that I bought on EBay. It fits under my seat. If my oxygen ever fails up high I'll fish it out, pull the pin and have oxygen for 15 min.

[DonMuncy]

Has anyone here had a personal experience of O2 failure; and specifically, does one recognize the symptoms such that they could/would use their emergency O2. I worry that should mine fail (even though I don't fly at those extreme levels) I would ignorantly go into a euphoric state and crash with an unused emergency source.

[Steve Dietrich]

On 2/9/2016 at 10:06 PM, carusoam said:

Steve,

Do you go as far as running two O2 systems at the same time or just a back-up ready to go?

With the small number of planes that have had run into O2 issues at high altitudes, I would be interested in info regarding a dual system where both are continuously running or some impressive automation that starts the back-up.

The old systems just don't do what they should that far up.

Best regards,

-a- 

A very late reply.  This is in the past tense as I sold the airplane a few months ago. 

The backup system was a smaller portable bottle with regulator and mask.  It was adjusted to the therapeutic flow rate (I forgot what the rate was but pretty close to 100%)  and had separate mask.  I had the flow rate set high assuming that I had been deprived for some time . Took only half turn on the cylinder to get it going .

The idea was to replace the entire system in one motion.  At 18,000 loss of oxygen is a problem   at 25,000+ it's a crisis

The early silicone rubber masks had a disturbing tendency for the  bag to detach from the mask,  easy to miss as the mask blocks the view.  I also had a very weird failure where the flowmeter got a hinged crack on the outlet side so it showed normal flow and looked normal but in some positions would leak 100% of the flow. .  After that I left a flow indicator in the line very close to the mask .  What identified the problem was  checking the blood sat with one of the meters Dr Achtel recommended after noticing an elevated heart rate.

I understand the sophistication of the pulse systems .   However,  if you own or rent the large cylinders oxygen is really cheap.  Add a Mountain High filler rig and you do it in the privacy and comfort of you hangar.   The tradeoff between pulse and simplicity/reliability goes to the hammer.   More sophistication for me would be a ear mounted saturation measuring system with an alarm. 

I have seen photos of some sailplanes with three systems for absolute redundancy  above 30,000 feet .  The primary system was one of the trick systems but the doomsday system was stone age simplicity

My other argument for  the manually adjusted systems is the ability to have a higher than standard flow rate

 

 

 

 

 

Edited April 23, 2016 by Steve Dietrich

[Steve Dietrich]

On 2/10/2016 at 7:34 PM, DonMuncy said:

Has anyone here had a personal experience of O2 failure; and specifically, does one recognize the symptoms such that they could/would use their emergency O2. I worry that should mine fail (even though I don't fly at those extreme levels) I would ignorantly go into a euphoric state and crash with an unused emergency source.

Don    I think the classic symptoms are fatigue  vision change    In my case i just felt unease and was aware of a higher than normal heart rate.

Drowsiness ,  headache  etc........  vision   but the danger for many is that it's like having a host who keeps your glass full,  you don't know how many drinks you have had and one of the symptoms is that you are less aware of the symptoms...... 

  There's no substitute for a sat measuring device.  Prices have come way down . 

 

 

[Bennett]

I see the thread is becoming active again. I used to fly my 261 at FL250 and 270 when there was a major difference in the tailwind component. I always wore a really (expensive) Scott mask with the built in system, and I positioned the red ball in a tube flow meter where it was In my normal scan. I had a second, portable, bottle strapped to the back of the co-pilot seat, with a. Identical mask and flow meter. I practiced switching from one system to the other and it only took a few seconds to switch masks and turn on the backup bottle. Never had to use the backup, but it was sure good to have it already set up and ready to go. I didn't have a pulse oximeter in those days, but I have one now. My current flying is less than 18,000' so use a single system.

[aaronk25]

How fast did that plane run (TAS) up at FL250 at max cruise?

I

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[Steve Dietrich]

MSC (maximum sensible cruise )  with the TSIO 360 MB motor is  75% to 78% which it will generate at FL 280   My recollection is 200+ K .  Usually you are there due to winds  which on the EUG - SMO run could be 70+ K .   It takes a while to get there and coming downhill eats a vast amount of distance .     333 FPM descent ,  180K (no wind)    240K wind  is 9 - 12 nm per 1,000 foot descent plus another 5 miles from the airport to get slowed to enter the pattern.   With wind the descent for the LA basin begins up around Fresno

[Bennett]

Sorry to be late in replying. TAS at FL250-270 was well above 200 Knits, but I was up there because of the west to east winds. On one flight I caught the lower band of the jet stream (winter) and ATC verified a ground speed of 315 Knots for New Mexico and Arizona. I never wanted to come down. On that trip my flying time from San Carlos to St Petersburg, Florida was 9 hours and 15 minutes with one fuel stop. (Long range tanks) . Took me 16 + hours to get back at 16,000' . I was always pleading with ATC let me start my descent 125 miles from my destination airport, and some times I actually got that sort of clearance.

[Steve Dietrich]

On 1/10/2016 at 6:53 AM, anthonydesmet said:

I currently own a 262 and couldn't be happier. As Bennett stated, the POH is basically the 252 for engine parameters. As already stated if you go with an earlier 261/262 you might miss some of the finer cabin features that your used to with the 86 J. Like the split back seats, nice white panel and adjustable pilot/copilot seats.  But whatever you decide you are going to LOVE being able to cruise in the mid-high teens (especially in the summer), nice smooth cool air at 170+knots.  Plus really take advantage of some the higher altitude tail winds. I am pretty sure speed brakes were standard for both mods and most likely on the 252 but just verify because you will definitely want them when you go turbo.

The Mooney 252 has electrical cowl flaps   which is something like buying a separate appliance whose sole function is to push down on the toaster .  Adds cost,  adds point of failure and takes the pilot further out of the system.  The Mod Works 262 adjusts the cowl flap with something like a prop control -   twist or push the buttion and pull or push.  The worst case scenario in the airplane is that you have an electrical failure on a low ILS approach when you have flaps and gear extended .  Especially if you now have to motor off to better weather.   Because you can not open the cowl flaps you are in danger of toasting the motor trying to climb with the gear still extended partial flaps   As the Mooney has three single points of fallure where a simple slide on connector can turn out the lights it is not idle thinking . 

Many of the 252's had yaw dampers.  Most of us can use the extra exercise and it keeps the pilot in the loop.   The airplane is incredible stable in roll and pitch if you trim and take your hands off the controls .  A tiny change in pedal pressure keeps the ball centered and the wings level.

[jlunseth]

On April 25, 2016 at 8:06 PM, Bennett said:

Sorry to be late in replying. TAS at FL250-270 was well above 200 Knits, but I was up there because of the west to east winds. On one flight I caught the lower band of the jet stream (winter) and ATC verified a ground speed of 315 Knots for New Mexico and Arizona. I never wanted to come down. On that trip my flying time from San Carlos to St Petersburg, Florida was 9 hours and 15 minutes with one fuel stop. (Long range tanks) . Took me 16 + hours to get back at 16,000' . I was always pleading with ATC let me start my descent 125 miles from my destination airport, and some times I actually got that sort of clearance.

Long range descent was one of the first adjustments I had to learn to make with my 231.  The first time I came in at high altitude from the west to Minneapolis (KFCM) I was still at 8k when I got to the airport.  It is as much art as science, because some days you will get high tailwinds all the way down and some days you will lose them fairly fast in the descent, so making low altitude when you are still 60 nm out means a slog in to the airport.  

Starting 125 out is not at all uncommon.  I frequently find myself starting my descent at the ND or SD border with MN, coming in to Minneapolis.  I use the desired VSI function on my 430.  I try to maintain 500 fpm for passengers ears, and generally want to start down when the 430 says the descent rate will be 450 fpm to my destination.  When you tip the nose over the speed will pick up quite a bit and that 450 fpm will quickly go to 500 or more.

I almost always get a clearance for a "slow descent" from ATC.  Almost never need to use the speedbrakes, but when you need em they definitely are handy, like around Chicago where they treat you like a jet or turboprop.

[Steve Dietrich]

On 2/9/2016 at 10:06 PM, carusoam said:

Steve,

Do you go as far as running two O2 systems at the same time or just a back-up ready to go?

With the small number of planes that have had run into O2 issues at high altitudes, I would be interested in info regarding a dual system where both are continuously running or some impressive automation that starts the back-up.

The old systems just don't do what they should that far up.

Best regards,

-a- 

Late response .

I understand and appreciate  the technology and sophistication of the O2 systems using pulse technology .  I'm also a fanatic about simplicity when it comes to stuff like this  and like the old constant flow  systems .  They operate with the simplicity of a toilet .  Happen to like the portable which I can adjust to suit desired flow.  Flying an approach after an 18 hour day  I would just land with the system supplying the extra O2.  Oxygen is really cheap if you don't need to buy it on the road and keep a tank and filler in the hangar.

The emergency system was pretty good sized and completely separate. My recollection was about 6 hours at 24,000  .  Part of the thinking is that some of the over the top flying is to avoid ice all the way down to the ground.  Another function of the portable system is that it has a high flow setting for a passenger with sudden health problems . 

Not a fan of the little bottles with a built on face mask for pilot emergency use as you have to use a hand to hold it. 

 

 

 

 

 

[Bennett]

A couple of comments. When I was up at FL 250- 270, I always had a back-up portable oxygen system hooked up with a second set of good quality (Scott) masks with built in microphone in case of failure of the built in system, and the flow meter (ball type) was placed against the panel so it was in my scan. From experimentation with a co-pilot CFII, I know I could only function for about 3 minutes at FL 270 without oxygen p>

Now that I am flying a J, I keep a small portable one person oxygen tank with its own oxsaver cannula already hooked up in case I have to climb for weather (or terrain), and I don't have to take the time to hook up everything

[Bryan1016]

Just picked up a mod works 231/252. First time turbo owner. Flew it home to AL over Rockies at 17,500...VFR time first flight. 28", 2500 rpm. Amazed at cool engine temps. Time will tell.

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[Mcstealth]

2 hours ago, Bryan1016 said:

Just picked up a mod works 231/252. First time turbo owner. Flew it home to AL over Rockies at 17,500...VFR time first flight. 28", 2500 rpm. Amazed at cool engine temps. Time will tell.

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Good times and good luck. Congratulations. 

 

Df