Vetteracer,
How much airspeed do you think would be lost in cruise with 1.5in on a 402 as you mentioned? How much would the stall speed increase?
Well, my comment was rather tongue-in-cheek, of course the boots will clean MOST, not all, off the leading edge. And the more you use the boots, the efficiency gets less and less, due to pieces that do not break off. If you blow the boots in a climb, with 1/4"-1/3" of ice, you risk bridging the boots.
{bridging = raising the ice, and expanding it, but not shedding it}.
This is a real problem, so I wait until I have at least 1/2" to blow the boots, and the faster the better. Ask for a block altitude, then push the nose over, gain 40 Kts, blow the boots, climb back to alt.
By the way, the FAA published a memo some years back discounting the bridging phenomenon. It is alive and real, trust me! They have since re-counted the memo.
The rest of the impact surfaces have 1.5" of ice, the tip tanks, the spinners, the nose, the windows, the inboard wing roots, most of the rudder, tips of the elevator, engine cowlings, etc. I find the best place to look for ice accumulation is on the temp probe, the ones that are drilled through the window. With this scenario a 402 at cruise power would loose about 30 knots, but handling is fairly stable. All 300-400 series Cessna’s are tail stall prone due to the location of the elevator. So any ice to speak of means limited use of the flaps.
BTW is it best to escape FZRA with an immediate 180 and a climb if you can and then retreat to an airport opposite of where the nasty stuff is? Seems right but wanted to know your opinion? Before we know it winter will be over and we will have to start worrying about the other weather killer again.... thunderstorms!!!
The best way to exit Freezing Rain would be a climb. It is warmer above to produce liquid rain. Or a climbing 180 I guess. I always climb when I run into any ice. You can ALWAYS go down, the other way can be difficult. Climb to the top, or find out what the tops are. When I was flying piston twins every day in the Midwest I always found out the tops, call the tower, call a NWA flight on ground freq and ask them to call the tops back on 123.45. The point is you cannot sit in the ice. Sitting in the ice is just running the clock down. You have to get out of it. Now, boots, hot props, etc buy you some time. How much time, depends on the rate of accumulation? Sit there long enough and now your climbing potential may be gone. I always try to get on top, find a layer, or an altitude were it is warm enough to stay clean. And an ice conscience pilot notes the temp at all altitudes on the climb out. Always thinking where can I go to stay clean, or get out. If you have no refuge, you need to find one or land.
I flew light piston twins single pilot day night IFR-VFR year round in the Midwest, T-storms every day in summer, and ICE from Sept, to April. It is a fact of life. You either learn to find a way to live with it, or find another job. It can be done safely if you have a respect for it.
The king Air hauls ice great and climbing to alt above the ice is the norm. Piston twins on the other hand is a whole diff game. During college I flew 6 days week, 3-5 hours a day. And it seemed that 2-3 times a year I really got hammered with ice, the rest of the times I was either able to get on top, below, find a layer, etc. So in the Midwest, 2-3 days a year of ice that was really bad, was not that big of a deal.
The best advice I could tell someone, about ice is Get on top and STAY ON TOP AS LONG AS YOU CAN. Going into MSP they always push light traffic down to 3K 50 miles out. YEAH right, Sit for 30 min plus vector time in moderate ice. But there were always some guys that would start down. I was one off them, ONCE. Had so much ice there was no way to level off, intercepted the glide slope inside the OM and was below the GS most of the way down. Sat in the ice for 45 mins, and after 30 mins the CB on the prop anti ice popped. Took me 15 mins to notice that the ice was not banging off the plane. Stay on top, in the clear until you have to start down. Ask for a vector, TELL them you are not going to descend into the ice. I wish I had a forum, or someone told me I could tell a controller what I wanted to do or needed to do. Controllers think you wont take a vector or a climb. I will do what it takes to stay on top out of the ice in piston twin until I have to come down.
If the ice was mod or heavy, I would stay on top and plan a 2K foot per minute descent outside the OM, to cross the OM at my desired intercept ALT, popping the boots all the way down. Then, at the Om, raise the nose, swing the gear and start down the slide at 140KTS (402-310), no flaps. Once the field was in sight, APP flaps at the most if any flaps at all.
Lesson 2
Clean screws will pull a dirty plane, dirty screws pull nothing. Loose the prop heat and that is bad news in heavy ice. You can try to cycle the props by moving them from high to low RPM quickly to try and twist the blades, Who knows if it works?
I think every good pilot should be well versed in ICE. It is one off the most dangerous weather phenomenon’s related to flying. And yet when I flew cargo full time, every Sept, there was some guy/girls that would pack their bags and quit. Did not even care to try, ride along with someone else, or get some experience. They were not shy about it, SEE YA, no ice for me. I often wondered if the two guys flying the ATR that crashed a few years ago were guys like this. If you want the title of Captain you owe it to your passengers to be well-versed on weather and ice before you gamble with their lives.
Mark
