Frankly, if I was an aircraft mechanic and you made demands like “not run the engine above 1600 rpm”, I would ask you to take your business elsewhere.
As Bosco says, there are good and bad shops. The bad ones won’t care, and the good ones would get p1ssed.
NCYankee wrote:
I only do one run up per flight day on the first flight of the day as I consider my previous flight as a long run up.
How did you get that approved? Most POH’s have the runup in the pre-takeoff checklist.
Pilot DAR wrote:
a run up might be simply check both mags at idle to make sure that they work at all
Same question. Most POH’s have a specific runup procedure.
Also I can’t imagine the tolerances for max drop and max difference between the magneto’s would be accurate at idle power, so you open yourself up to other potential safety of flight issues i.e. taking off with inadequate/fouled magneto’s.
Why use these non-standard procedures when a run-up ‘on the run’ solves all these issues?
You’re about to take-off where you require the most out of the engine to meet the calculated performance of the airplane. To elect to skip the recommended/approved engine checks sounds a little … inadequate.
when a run-up ‘on the run’ solves all these issues?
I would offer the opposite view.
A stationary run-up gives you the opportunity to inspect the ground in front of the plane.
A moving run-up doesn’t, but the stones will get sucked up into the prop just as nicely.
The time one could get nicks in the prop is IMHO only if one did not inspect the ground in front of the plane. And yes most of the time this risk cannot be avoided, because in normal aviation you taxi off the parking position and do the run-up further on. On can still eyeball the ground at that point though, and check for obvious rocks.
The other problem with a moving run-up is that you need to keep an eye on not driving into something while watching the instruments – rpm, fuel flow, EGTs etc to make sure all 12 spark plugs etc are firing. I have seen the Trilander ops to the Channel Islands do moving run-ups, on the brakes…
Archie wrote:
How did you get that approved? Most POH’s have the runup in the pre-takeoff checklist.
Why would he need approval?
Flying off dirt strip Australia I was advised to start engine and taxi simultaneously and do the mag check on the roll. Some people found this difficult to do because of their embedded training mentality. Occasionally, I like to do a full RPM check, usually over a suitable piece of grass, to ascertain that I’m obtaining maximum static RPM. This is also required after fitting/refitting a prop to adjust governor or pitch stops.
Archie wrote:
I only do one run up per flight day on the first flight of the day as I consider my previous flight as a long run up.How did you get that approved? Most POH’s have the runup in the pre-takeoff checklist.
Pilot DAR wrote:
a run up might be simply check both mags at idle to make sure that they work at allSame question. Most POH’s have a specific runup procedure.
A fair point.
Flight Manual wording can differ (so the following cannot be absolute) but I randomly selected from my Flight Manual library that for the 1982 C 172RG to consider this point. I cannot find in a preamble the wording I have seen from time to time which reads something like “use these procedures in conjunction with good judgement”. What I did find in that specific Flight Manual (Section 4) was the statement: “MAGNETO CHECK The magneto check should be made at 1800 RPM as follows.” ….
If I felt that a run up over a loose surface could damage a prop, I would apply my judgement to determine that in that situation, a magneto check should not be done at 1800 RPM. A check of lesser value can be done at idle RPM. Doing this does not generally conflict with following flight manual procedure. I admit that one of my first flights in 182 as a very new pilot, I nearly trashed a prop trying to power my way out of soft ground. The prop survived, but it cost me an overhaul, and I learned my lesson. A number of years ago, I was involved in flight testing the Lycoming 360 powered DA-42. during our test program the aircraft was “borrowed” for a couple of days for a show a few hundred miles away. When it was returned, it had different props installed (which affected our continued testing). Upon inquiry, it was reported that the pilot had ruined the original props during a loose surface runup. ONE loose surface prolonged runup can be enough to ruin a prop – don’t risk it!
JasonC wrote:
Why would he need approval?
There are many levels of approval, but it all boils down to this crude principle: how will it look in the accident report? Going against the approved documents (i.e. runup procedure contrary to POH/Engine manufacturers recommendations) never looks good IMHO.
Peter wrote:
A moving run-up doesn’t, but the stones will get sucked up into the prop just as nicely.
Peter wrote:
The other problem with a moving run-up is that you need to keep an eye on not driving into something while watching the instruments – rpm, fuel flow, EGTs etc to make sure all 12 spark plugs etc are firing. I have seen the Trilander ops to the Channel Islands do moving run-ups, on the brakes…
Pilot_DAR wrote:
“use these procedures in conjunction with good judgement”
I’m sure stones are not sucked into the prop due to their inertia. I can hear the ‘pinging’ sometimes even when stationary at low RPM, but never when I move. Is your experience otherwise? Perhaps move a little faster.
With my 20cm of prop clearance, and a good number of dings in the prop, stones must be getting sucked into the prop somehow… They are not jumping up into the prop on their own 
I would guess there is a range of stone weights within which they get sucked up and cause damage. Smaller stones will get sucked up but won’t ding the prop. Big stones (say 1kg) won’t get sucked up.
Archie wrote:
To use judgment to save a bit of money on maintenance somehow doesn’t quite cut it I think?
It’s not about saving money on maintenance, it’s about not damaging the plane! If you’re carelessly running up, and nick a prop (as the photo showed) would you know that you’d done that damage before you took off for the flight? It’s up to the pilot to use their best judgement to prevent unsafe situations or damage.
Besides said problem can be prevented by doing the runups ‘on the run’.Quote
Run ups on the go might be a solution, though I hardly see the authority approving that, eyes out while taxiing! If landplane pilots are running up on the go, they have made that judgement, as the run up being more important to them than attention to taxiing, which I can accept in some circumstances, but certainly not all. We do run up on the go in floatplanes, as there is no alternative, but usually, there is more room to point to the plane, and then not watch for a few seconds.
If landplane pilots are running up on the go, they have made that judgement, as the run up being more important to them than attention to taxiing, which I can accept in some circumstances, but certainly not all.
I don’t have any first hand experience in seaplane flying (yet, I am just heading to the seaplane flight school as I write this) but from an instructors view, I can confirm that on new students the occupation doing either a runup or taxi the aircraft is enough to fill the attention. Especially when using the check lists before and after the runup. That gets better with more experience, but if the aircraft is moving I usually require my students to pay attention to the move. I even stop for briefings between circuits.
Having said that, of course things like the run up will occupy less attention as the pilot becomes more experienced and knowledgeable.
But in my experience, I have witnessed more prop damage during operations on concrete grounds, than from normal grass airfields. And if possible I tend to perform the runup at the parking position when I have cleared the area in front of the props.
