MT to TBO

I was looking at the MT site and found the TBO recommendation for their propellers. http://www.mt-propeller.com/pdf/sbs/sb1aa.pdf lists the TBO for all of the MT propellers. They vary between 1000 and 2000 hours. They ALL have a TBO of 72 months from the date of installation or 24 months from the date of manufacture (whichever is earlier). I thought this may be of interest to those of you that are considering the MT propeller. I am now inquiring about their fixed pitch prop.

How much does the overhaul cost and what is involved?

I guess they mean 72 months from installation and installation must be within 24 months of manufacture or an overhaul is required...

Thomas

MT Overhaul

I wouldn't get too hung up about the 72 month TBO of an MT prop. I think its really a strip and inspect. I ran a 4 bladed MT on a 300hp airplane for 4 years and had no problems at all, the baldes were in good shape. An overhaul on an MT is not the same as a metal bladed prop - the blades do not have to be ground down, and there are now several service centers around the country. I think the 72 month limit is at the behest of the European authorities - what's the TBO of a Hartzell?

TBO of a Hartzell

From their FAQ: http://www.hartzellprop.com/kitplane/kitplane_faqs.htm

"What is the recommended time-between-overhaul (TBO) for Hartzell propellers?
For new manufacture "compact" propellers installed on piston aircraft it is 6 years or 2,400 flight hours, which ever comes first. Most used Hartzell propellers (built before 1997) have a recommended TBO of 5 years or 2,000 flight hours. Full TBO details may be found in Hartzell Service Letter 61V."

Does anyone out there know what it cost to OH the Hartzell or the MT? That would give the best idea. Not knowing the cost I would lean toward the Hartzell since the TBO is pretty close to the TBO of the engine MOH.

Prop Overhaul

I recently paid $2800 to overhaul a McCauley 2-blade prop. However, if the MT & Hartzell TBOs are both 6 years for new props where's the difference? A metal prop can only be overhauled a certain number of times (3 I think) before the baldes are too thin. Where as a composite prop does not have that limitation as the blades do not have to be ground down. My preference is for an MT or Whirlwind because they are lighter and much more smooth.

Pete

Difference?

Pete, In looking at the MT - TBO Service Bulletin you are correct. There is not a lot of difference to be discerned. I looked up the TBO of the 9 MT Props that VAN's sells (per his online catalogue) and interestingly only two are listed in the SB. For those two the TBO is 1800 hrs which is only 700 hours less than a Hartzell. The blade OH factor that you mentioned may very well factor into a "break even" arrangement.

My point in sending out the thread was that some have a TBO of 1000 hours. It would probably be wise to find out what the TBO is for a propeller before purchasing it. Since 7 of the MT propellers that VAN?s sells are not listed in the SB I personally would do a little inquiring before I purchased. That way there are no surprises.
George

Just a slight clarification.
The time limit TBO is 72 months from installation on the engine. There is a 24 month period allowed for this installation to occur. Otherwise, the time TBO is 72 months from date of manufacture.
The maximum flight time TBO is 2500 hours. When the first 3 propellers of a specific designation have been overhauled, the TBO time increases to the next level. The flight time TBO in Service Bulletin # 1 is reviewed as the TBO flight time approachs to verify the latest flight time TBO information.
Jim

Hartzell Overhaul cost, Smooth metal props

penguin said:

I recently paid $2800 to overhaul a McCauley 2-blade prop. However, if the MT & Hartzell TBOs are both 6 years for new props where's the difference? A metal prop can only be overhauled a certain number of times (3 I think) before the blades are too thin. Where as a composite prop does not have that limitation as the blades do not have to be ground down. My preference is for an MT or Whirlwind because they are lighter and much more smooth. Pete

Click to expand...

I paid $1,500 for a Hartzell HC2YK overhaul. I asked the shop if there are common problems which they see and the answer was most come thru overhaul with no problem or extra cost. The fatigue life of a Hartzell, depending on model of prop and engine (electronic ignition or HC pistons) is between 8,700 hours to 20,000 hours! Taking the low limit and 200 hours a year, which would be over 43 years! The high limit 100 years worth if flying. What would a Wood based MT prop with composite cover be like in 40 or 100 years? No one knows, since MT has only been in business since 1981. Of course I will not care about props in 100 years. Also, even though MT has certified props, many of their props are not approved on any cert aircraft. This is not a put down of MT, but credit must be given to Hartzell for supporting the experimental market and testing their props on experimental airframes with experimental engine configurations.

As far as smoother, I am not sure how you know this Pete, since it is subjective. May be you have never flown a smooth metal bladed prop, and the metal props you have flown don't reflect all metal props. I understand the new Hartzell blended airfoil prop is very smooth. Also it does not have a RPM "range" restriction as some state. The limitation is a single power setting when using electronic ignition and/or HC pistons, "do not operate above 22" below 2350 RPM," which is not a "range" or affect normal operations.

My HC-C2YK/F7666-4 is very smooth and I am happy with it, but I did need to get it balanced. After getting a proper ballance, I was very happy with the feel. Any "wood" based blade, like the MT composite covered wood core blades are going to be ?naturally? smoother. Wood has natural dampening qualities. However how much smoother? I know a good tracking prop, well-balanced, even with metal blades, is going to be pretty smooth. You are not going to totally tame engine vibrations with the prop alone. With metal blades, you can feel some RPM's are smoother than other RPM's, due to harmonics. I don't find it objectionable, but if you are paying attention you can detect subtle difference. It is very easy to avoid these narrow RPM bands. Not sure if vibs are all prop or the combo of engine/prop vibrations. The Wood based prop will be smoother over a wider RPM range, but metal props are not as bad as people make out, especially when you take cost and availablility of service for the Hartzell into account. George