IFR approach power settings & flap limitation speeds

[Bob Leve]

I have two questions:
First, what is the limiting speed on using 15 degree flaps for a M-5 235C. I assume that the flap limit speed on the A/S indicator refers to full 35 degree flaps. I am asking because close to the runway on an IFR approach I find that I would like to have my flaps 15 degree extended before I break out of the overcast. Yet, I don't want to fly my approach at 90 MPH or below (the flap limitation speed) as that makes for a long approach and in a busy AP the controllers will expect 90 K and might get cranky. Of course I want to be at 75 MPH for the last few hundred feet for a proper landing and I am having trouble slowing the A/C in that short space and altitude.

Second, what might be the proper power setting for a 90 MPH or 90 K approach speed with 15 degrees of flaps and a 500 feet/ minute decent. So far I have found that I need to go to minimal manifold presure and 1800 RPM.
Any advice from more experienced people would be appreciated.

Bob

[rjb]

I got my PPL in 2005 and I got my IFR capable MX-180C in 2006 in which I got my instrument rating in 2007. Although I have gray heir, some from my flying, I'm only giving datapoints not "pearls of wisdom".

I generally fly 90 knots from IAF to FAF. But if it's Salinas ILS with a big arc, I don't slow from 110 until closer to 5 miles out.

As to flaps, I don't lower any flaps until 95 mph (my ASI flap range starts at 100 mph).

Any runway I'm doing a precision IMC landing on is easily comfortable with no flaps and if it's non precision, if I don't see it in time to slow down from 90 knots, I don't feel comfortable enough to land. (But I do feel comfortable slowing down rather quickly.)

If I'm in IMC, I could care less about pleasing ATC; if I'm practicing with a safety pilot in VFR, whatever I feel I can do comfortably to please ATC is
a consideration.

My CFI drilled in that ATC is there to help you not vice versa.

-Dick

[a64pilot]

All my IFR approach work is flown at 90 kts. Top of the "A" category speed , plus she is real stable at 90 kts and it gives me some room to err.
An ILS in my M-6 is with mixture full rich, prop all of the way in, flaps at 0 and around 15-18"MP at glide slope intercept. That's for close to sea level airports of course. I think the prop is around 2000 or so, I'm not sure. That way all I have to do when I break out is reduce the throttle and land, one notch of flaps if I want to, but it will land just fine at 0 flap. Or if I have to execute the missed, all I have to do is add throttle, call approach and fly the airplane. I don't want to be having to do any re-trimming, flap retracting, or anything not completely necessary on the first stages of the missed.
The white arc is for any flap position other than 0 or -7, I'm sure. Pretty sure you will get some "working" rivets if you use flaps above the white arc speed. Mine had some "working" rivets when I got it, I replaced them several hundred hours ago and have had no further problem. I think the previous owner may not have been paying attention to the white arc.

[Kirk]

I fly most my approaches clean at 90 KIAS also, the airplane handles nicely there, the math for time/distance is easy. Any runway I've flown to has enough length to just land clean or with one notch of flaps.

Power settings I can't really say. I run the prop and mixture up 1 dot below the glideslope then start a power reduction 1/2 dot below until my desired sink rate is reached. It's usually right down at the bottom of the scale on the MP.

I'll do ILS in busy airports at 120 KIAS sometimes. You fit into the traffic flow better and for me, it gets me closer to the speed and sink rates in use for the aircraft I fly at work.

A few years back I had to grin when I was flying at 120 KIAS after being asked to "keep the speed up on the approach". Don't think the controllers expected that much since they called the Regional Turboprop ahead of me and said: "Keep your speed up, you have a Maule behind you overtaking by 30 knots"

Not something we get to hear every day.

Kirk

[Mauledriver]

In my MX7-180a, I generally fly real life approaches with 2400 rpm and zero flaps for close in vectoring. Trimmed for level flight, I can then go into -8 and 2200 which gives me 500 to 600 fpm at over 90 knots.

When I pop out, I chop the power, and apply flaps landing with +8 on most occasions.

When flying low approaches I usually do it at big airports. The speed makes everything easier including the flying. Never any trouble slowing the Maule down to landing speed.

Doesn't anyone else use the reflex flaps for ILSs?

[aero101]

A rule of thumb that I use and will put you in the ballpark with most airplanes... -1" MP = 100 FPM on the descent... So if you stabilize / trim at whatever speed you're wanting to fly the approach at ( I usually try to use 90 in actual IFR, and faster when practicing to assist ATC in most airplanes I fly) , then just before intercepting the glideslope, pull out 5" of MP, you should be pretty close to being able to fly the glideslope at the trimmed airspeed. I agree with most in that I don't pull in any flaps until runway environment in sight as most ILS runways, you've got enough runway in front of you to land no flaps in needed? Or just pull up the nose when runway in sight and dump in full flaps?

[andy]

I have a 1986 MX-7-180. At busy airports I used 115 mph (100 kts) in most approaches to avoid sequencing problems with faster aircraft. At an airport that isn't busy, 90 kts works fine. I don't use flaps until I'm about 2 miles from the runway ( mine are -7, 0, 24, 40, 48 ). Power settings for most of the approach after the IAF are 19" and 2300 RPM. For ILS approaches, I've found that 16"-17" MP and 2300 RPM work pretty well to keep me on the glideslope. While descending I worry about shock cooling, especially in cold weather, so I prefer to reduce RPM first to the bottom of the normal operating range (2250) and gradually reduce MP to the target descent rate. For landing I use 65 mph airspeed and around 1600 RPM for a 500 FPM descent rate, adjusting the throttle to keep the touchdown spot steady in relation to the glareshield.

Andy