Flight Safety Australia article question
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Flight Safety Australia article question
Have just received the Sept/Oct issue of FSA. Page 16 has article called "Mags on Both" about a pilot who inadvertently took off on one mag. The analysis by FSA gives a recommended sequence of mag checks. Is this official CASA policy or just someone's perceived good idea. There is no end of perceived good ideas by pilots. The article states "Many pilots do not use the correct technique (of checking mag operation ?)
Its yonks since I flew a Cessna but I thought the the positions of the key starting from the off position being on the left of the switch, then turning the key clockwise from off, next position is Left, then after that is Right then after that is Both. If that is correct, the way I read the description in the FSA article it infers that "two clicks left from Both means the key is on Left magneto. That being so, the article says that makes the left mag inoperative.
I am rusty on this but if the key is on a mag position such as Left does not that mean you are operating on the Left magneto? The article implies with the key on Left the left mag is the one that is switched off. Which is correct?
Also the article states that an aircraft should not hold in the lined up position for pretake off checks unless you have a sound operational reason to do so, such as conducting an over-speed governor check on first flight of the day. I am mystified on this. Why cannot the over-speed governor check be done in the run up bay or holding point clear of the runway.
The analysis by FSA then says "Finally, a check of temps, pressues and RPM" should be checked on the take off roll. Surely this is an overkill. The place to check the temperatures and pressures (oil pressures) is during the run up - not in the middle of a take off. In any case a sudden change of temperature should not be cause for an abort and exactly how much temperature change constitutes an abort decision?
The article seems to indicate the particular Cessna 152 had a cruise prop. This would give a significantly lower minimum static rpm than an aircraft with a normal prop. The article did not say if the pilot was aware of a cruise prop indicating lower RPM - only that one Cessna accelerated slower than his other Cessna. If the take off was on one mag only, chances are the pilot would have not picked the slightly lower RPM than already expected from a cruise prop.
Its yonks since I flew a Cessna but I thought the the positions of the key starting from the off position being on the left of the switch, then turning the key clockwise from off, next position is Left, then after that is Right then after that is Both. If that is correct, the way I read the description in the FSA article it infers that "two clicks left from Both means the key is on Left magneto. That being so, the article says that makes the left mag inoperative.
I am rusty on this but if the key is on a mag position such as Left does not that mean you are operating on the Left magneto? The article implies with the key on Left the left mag is the one that is switched off. Which is correct?
Also the article states that an aircraft should not hold in the lined up position for pretake off checks unless you have a sound operational reason to do so, such as conducting an over-speed governor check on first flight of the day. I am mystified on this. Why cannot the over-speed governor check be done in the run up bay or holding point clear of the runway.
The analysis by FSA then says "Finally, a check of temps, pressues and RPM" should be checked on the take off roll. Surely this is an overkill. The place to check the temperatures and pressures (oil pressures) is during the run up - not in the middle of a take off. In any case a sudden change of temperature should not be cause for an abort and exactly how much temperature change constitutes an abort decision?
The article seems to indicate the particular Cessna 152 had a cruise prop. This would give a significantly lower minimum static rpm than an aircraft with a normal prop. The article did not say if the pilot was aware of a cruise prop indicating lower RPM - only that one Cessna accelerated slower than his other Cessna. If the take off was on one mag only, chances are the pilot would have not picked the slightly lower RPM than already expected from a cruise prop.
Last edited by Tee Emm; 23rd Oct 2006 at 13:35.
As power is initially applied I used taught check RPM, Oil T's + P's. This took perhaps a matter of 5 seconds. If you are going to run off the runway in a C152 in 5 seconds you probably have other issues. The static RPM in the flight manual is (from memory) 2215-2315RPM. I would imagine this range would take into account a Cruise v Climb prop, as there is no reference made with those figure of leeway for either type of prop.
I don't recall how the mags work exactly, but I was under the impression the left switch meant you were running on the left mag, hence right mag was earthed and vice versa. Happy to be corrected on that point. I do use (and teach) the technique in the magazine of one mag, both, other mag then both. Gives you a good reference as to what the actual drop is on each individual mag.
I don't recall how the mags work exactly, but I was under the impression the left switch meant you were running on the left mag, hence right mag was earthed and vice versa. Happy to be corrected on that point. I do use (and teach) the technique in the magazine of one mag, both, other mag then both. Gives you a good reference as to what the actual drop is on each individual mag.
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People, this is not that hard...
Mag switches I have seen (Piper, Cessna etc) are, left to right: OFF RIGHT LEFT BOTH START. Therefore the description in the magazine is correct. LEFT mag selected means the LEFT mag is OPERATING, RIGHT mag EARTHED (ie not operating). Vice-versa. If there is NO DROP when we select a single mag, it usually means an earth wire is broken and we stay away from the prop for a while due LIVE MAG.
As for pretakeoff checks, it's not that hard to check mag position entering the runway as you hit the transponder/strobes etc. Check the oil T/Ps when you roll. I am happy to do the runups with the oil temp 'off the stop', but takeoff with it out of the green? No thanks! And if the RPM isn't somewhere in the green arc and close to the red radial, it's probably a good reason to stop.
Anyway, I'm off to read the article
P.S. a quick search turned up an old article from Flight Safety which describes typical ignition systems very well. It can be found HERE
Mag switches I have seen (Piper, Cessna etc) are, left to right: OFF RIGHT LEFT BOTH START. Therefore the description in the magazine is correct. LEFT mag selected means the LEFT mag is OPERATING, RIGHT mag EARTHED (ie not operating). Vice-versa. If there is NO DROP when we select a single mag, it usually means an earth wire is broken and we stay away from the prop for a while due LIVE MAG.
As for pretakeoff checks, it's not that hard to check mag position entering the runway as you hit the transponder/strobes etc. Check the oil T/Ps when you roll. I am happy to do the runups with the oil temp 'off the stop', but takeoff with it out of the green? No thanks! And if the RPM isn't somewhere in the green arc and close to the red radial, it's probably a good reason to stop.
Anyway, I'm off to read the article
P.S. a quick search turned up an old article from Flight Safety which describes typical ignition systems very well. It can be found HERE
Last edited by jetstar1; 24th Oct 2006 at 00:08.
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The analysis by FSA then says "Finally, a check of temps, pressues and RPM" should be checked on the take off roll. Surely this is an overkill. The place to check the temperatures and pressures (oil pressures) is during the run up - not in the middle of a take off. In any case a sudden change of temperature should not be cause for an abort and exactly how much temperature change constitutes an abort decision?
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Thanks for replies. Interesting points made.
Awo157. You said:
In fact this range you mentioned does not take into account a cruise versus climb prop as they are very different figures. The minimum static rpm is not the same for all Cessna's. If the particular aircraft has a cruise propeller installed, the Flight Manual for that aircraft will have a Supplement at the back of the FM which includes the minimum static rpm for that specific propeller installation. For a cruise prop I believe the min static rpm is relatively low at around 2050-2100 - but like I said, check the Supplement.
On the other hand the normal propeller min static is in the general range from 2280-2380. Before you fly any aircraft with a fixed pitch prop the pilot should carefully note the published min static rpm especially if the operator has failed to advise that the aircraft may have a cruise prop. That info is found sometimes in the Flight Manual under Limitations or in the POH same place. It should also be remembered that the published minimum static rpm is based on carb heat off and mixture control leaned to maximum rpm.
With regard to oil temp in the green arc before applying take off power, there is no operational requirement for this and in cold weather it is quite normal for the oil temperature to not be in the green arc until well into the climb after take off.
Further to that point, if you read page 4.23 (Cold Weather operation)of the Cessna Model 152 Information Manual published by the Cessna Aircraft Company it may be of interest that:
Quote: "During cold weather operations, no indication will be apparent on the oil temperature gage prior to take off. After a suitable warm up (2 to 5 minutes at 1000rpm) accelerate the engine several times to higher rpm. If the engine accelerates smoothly and oil pressure remains normal, the airplane is ready for take off."
There is no published Limitation in the Cessna 152 POH regarding minimum oil temperature for take off but there is a maximum oil temp of 245F.
There certainly is no requirement to monitor the engine oil pressure and oil temperature during the take off run. On the contrary the pilot should be concentrating on keeping straight on the take off run especially if a strong crosswind is apparent. The time to check these engine parameters is during the run-up procedure.
Awo157. You said:
The static RPM in the flight manual is (from memory) 2215-2315RPM. I would imagine this range would take into account a Cruise v Climb prop, as there is no reference made with those figure of leeway for either type of prop.
On the other hand the normal propeller min static is in the general range from 2280-2380. Before you fly any aircraft with a fixed pitch prop the pilot should carefully note the published min static rpm especially if the operator has failed to advise that the aircraft may have a cruise prop. That info is found sometimes in the Flight Manual under Limitations or in the POH same place. It should also be remembered that the published minimum static rpm is based on carb heat off and mixture control leaned to maximum rpm.
With regard to oil temp in the green arc before applying take off power, there is no operational requirement for this and in cold weather it is quite normal for the oil temperature to not be in the green arc until well into the climb after take off.
Further to that point, if you read page 4.23 (Cold Weather operation)of the Cessna Model 152 Information Manual published by the Cessna Aircraft Company it may be of interest that:
Quote: "During cold weather operations, no indication will be apparent on the oil temperature gage prior to take off. After a suitable warm up (2 to 5 minutes at 1000rpm) accelerate the engine several times to higher rpm. If the engine accelerates smoothly and oil pressure remains normal, the airplane is ready for take off."
There is no published Limitation in the Cessna 152 POH regarding minimum oil temperature for take off but there is a maximum oil temp of 245F.
There certainly is no requirement to monitor the engine oil pressure and oil temperature during the take off run. On the contrary the pilot should be concentrating on keeping straight on the take off run especially if a strong crosswind is apparent. The time to check these engine parameters is during the run-up procedure.
I had a situation where an incorrectly installed oil filter was spewing oil throughout the taxi and run up. The engine finally ran out of oil in the take off run as indicated by losss of pressure and misbehaving prop governor. I will continue checking power output during the take off run. Lots of things are not a requirement but are good airmanship. Basic stuff really.
Another thing to do whilst on the rwy is confirm dg alignment and correct rwy heading. Suprising how many so called professionals dont do the basics.
Another thing to do whilst on the rwy is confirm dg alignment and correct rwy heading. Suprising how many so called professionals dont do the basics.
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When a cruise prop is installed on a C152, one of the requirements is that a placard be displayed on the panel showing the minimum static RPM is 2100 and that the max continuous cruise RPM is 2440, as both figures are at odds with the AFM.
As for the checks during the takeoff roll, I can't imagine why you wouldn't check the gauges - particularly in a low performance aeroplane like the 152. EFATO is not my idea of fun, and if a simple 5 second check can help avoid the situation, it's worth it.
As for the checks during the takeoff roll, I can't imagine why you wouldn't check the gauges - particularly in a low performance aeroplane like the 152. EFATO is not my idea of fun, and if a simple 5 second check can help avoid the situation, it's worth it.
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.......and let's face it - in an aircraft like a C152 one has plenty of time to check these things before committing oneself to the air. RWY behind you, sky below, and all that stuff!
Oh well there you go, I have never encountered a C152 with a cruise prop. Happy to be corrected.
As to checking the oil, the smooth acceleration might work with a C152, but are you going to rely on that when you move up to a higher performance aircraft? Would you try that with a Baron? (I don't fly Baron's, just a type that sprung to mind). It's just a small, simple habit we try to build in the early stages for when people progress onto more advanced aircraft. Same as checking Gear down on downwind. I hope it's there on C152 and if it's not, there is bugger all I can do about it. Just another habit so people will hopefully do it the first time they fly a retrac.
Agree with you though, nothing beats good knowledge of your aircaft. Do whatever the Flight Manual says.
As to checking the oil, the smooth acceleration might work with a C152, but are you going to rely on that when you move up to a higher performance aircraft? Would you try that with a Baron? (I don't fly Baron's, just a type that sprung to mind). It's just a small, simple habit we try to build in the early stages for when people progress onto more advanced aircraft. Same as checking Gear down on downwind. I hope it's there on C152 and if it's not, there is bugger all I can do about it. Just another habit so people will hopefully do it the first time they fly a retrac.
Agree with you though, nothing beats good knowledge of your aircaft. Do whatever the Flight Manual says.
