Skydive Pilots Around??

[avbug]

Slipping off the step can be humerous, but it can also hurt. Spin off feet first to the rear, and a concussion can result, not to mention the possibility of grabbing a cutaway handle or a reserve handle while reaching for grips on the step. Sometimes it's a joke, but not when someone gets hurt.

Idle descents can cause thermal damage. Call it "shock cooling" if you will; I've changed enough cracked cylinders to have a healthy respect for the potential cosequences. Backlash damage to engine accessory drives and to the engine itself, any time the slipstream is driving the propeller, is also a real factor to consider. Idle descents in a piston airplane are stupid things to do, smack of exceptionally poor airmanship, and can quickly unnecessarily reduce the life of the engine or it's components.

Sadly the time it's most likely to be manifest isn't in the shop during an inspection; it's during a hot and heavy takeoff with an airplane full of student skydivers.

 

[TonyC]

Why not do an idle decent in a piston powered airplane?

You're joking, right??

NO, I was dead serious. That's why I asked the question, EVEN at the risk of being ridiculed. Thanks for not letting me down.

 

[Tug Driver]

so if one doesn't utilize idle decents, how would one practice engine out procedures?

 

[avbug]

There's a big difference between doing an idle descent from eighteen thousandfeet, or twelvethousand feet (whatever is being used for jumping on a given day), and a training occasional maneuver.

I did some work on a 182 last year that had been with a particular jump operation for a decade. In reviewing the logs, seldom had it gone fifty hours without a cylinder change. That wasn't due to improper installations, or severely bad maintenance. It was due to too many full power climbs with not enough cooling airflow, and too many power off descents...not to mention very likely poor mixture practices.

Pulling the power to idle is hard on an engine, period. Making a comparison between training operations, and operational flying, isn't a good one. In the former, we're attempting to briefly show a slice of what could happen, and in the latter, we're into the every day methods of how it should happen. Big difference.

Additionally, why would you stress the airplane any more than necessary?

 

[huncowboy]

so if one doesn't utilize idle decents, how would one practice engine out procedures?

I >>think<< what avbug means by idle descents is when you come down kind of fast with idle for an extended time from a higher altitude. If he meant something else he will surely correct me.

When you're practicing engine out, you typically begin from 1500-2000' or even lower. Of course you can do it from higher but there is no point in spending training $$ for keeping that 70KIAS for X minutes longer while you are done with all the procedures.
Another thing is that when you practice engine out you pitch for a relatively slow airspeed that may not give such a cooling rate. But in winter I can imagine even a 2-3 min descent at 70KIAS can cool the engine extensively.

During my training, so far, the only maneuver that always resulted in the cylinder gauge needle hitting the left side of the scale was emergency descents.

As always: I hope someone will correct me if I was wrong with the above.

 

[bugchaser]

Huncowboy is right. Like Avbug said, there is a huge difference between a practice p. o. descent and a rapid descent from altitude. In my opionion, temp management is a skill that many pilots have not grasped. Another very important thing which Avbug touched on is the backlash damage that can occur when the engine is being driven by the air. You should always try to keep the prop pulling the airplane instead of being driven by the slipstream. This is important in all powerplants and is absolutely necessary with some.

 

[414Flyer]

I used to fly a twin bonanza for a DZO, and I always tried to make sure the engine was turning the props, and wasnt in a low power situation where idleing down, and having the airflow turn the prop.

Its not good for piston engines, especially if geared, like the twinbo and C-421 are.

 

[Sctt@NJA]

Good info on this thread.

I had a hard time keeping my boss happy when I did the jump pilot thing. Not only did he not want to be blasted by the prop but he didn't want to lose any altitude either. The strictest rule was "don't shock cool the engine" yet they would flip out over every tenth of an hour on the engine. It seemed like they wanted the impossible. Either too much prop wash, or just right but "we lost 50 feet of altitude, nobody likes to give that up".

I could come down from altitude fast and risk shock cooling, or I could take my time and be conservative, or something in the middle, didn't matter it was never right.

 

[avbug]

The idle cut on jump run does mean a descent and small loss of altitude, but it's inconsequential. There is no danger of shock cooling the engine during that cut. You're already slow and descending slow; the reduced relative wind means less push on the prop to drive it. It's also a safety issue; you stand a better chance of jumpers making a clean exit and not grabbing a reserve handle or cutaway by mistake. Safer for you, safer for them. You can decend at that airspeed all day long, keeping it slow, and it's easier on everyone. At that point, you end up having to power up for the descent, and you're already slow...you don't have to slow down to come down.

Door open and the drop is nothing more than getting the jumpers out while you set up the descent.

 

[MED]

britishguy,

any problems closing that door after the monkeys jump away?

 

[PropsForward]

Well, I see from the other posts that you have been fully briefed that cross controlling the aircraft is fine.

I flew skydivers for about a year and I would not pass that experience up for nothing. Most new skydiving pilots get many complaints the first few times up. Not getting the spot right, taking to long to climb, or having to fly back to the airport after reaching the assigned altitude, etc. You will learn quicky and in time be tearing your very own holes in the sky as apply your new flying skills to the demands on commercial aviation.

On word of advice though, the aircraft tend to be on the shady side of being airworthy and the operator does not give a s#!t about you. Protect yourself at all times and make sure the aircraft is airworthy. If something a "dumb" as the manifold pressure guage is broke, then don't fly it. It will be you that gets the ding on your record for flying it.

Happy Safe Flying!

 

[plattsburgher]

my two cents

British Guy,

I have a couple of summers flying a 182 for a DZ. The jumpers don't care at what speed you are flying, they don't like the prop blast. I used to reduce the pitch a bit to let the aircraft accelerate the last few hundred feet prior to the desired altitude (while still in a climb). This allowed me to keep the prop blast low (making the jumpers happy) and keep the airplane from stalling the right wing (keeping me happy).

The other advice about the rules is right on target. You are the adult and it is your ticket on the line. If it isn't VFR for your airspace the jumpers won't care--I guarantee you will be told that they "don't mind jumping through a cloud". Keep an eye on people as it gets later in the day, don't let them on board if they are drunk or high. Most of the planes will have only what is required for VFR as far as equipment goes. Know what you have to have.

Then go have fun. It is a great way to pick up some good PIC time and a lot of good memories.

 

[FN FAL]

Shock cool this...

This is an oldie, but this type of thing happens. In fact, it happened last week in Illinois with similar results. The more level and stress free you can make the jump run when you are flying, the less chance you are going to have of someone getting hurt while flying jumpers.

To the original poster of this thread, good luck and stick with it. I think you'll get the hang of it in no time. Consider this next time you go up and the door opens. Look at the ball...guess what, it's out of the dog house! Cross control it back to center. Then the jumpers get out on the step, look at the ball...guess what, it's out of the dog house! Cross control it back to center. You might be cross controlling the plane, but you are cross controlling it to get it back to coordinated flight...If you have enough control authority, that is. Oh, don't mind me, I only got about 1,200 hours flying jumpers and at least 600 jumps...and yea, as a jump pilot, I have had to dead stick twice and a jumper had an open parachute container in my plane once while the door was open. I had to pin that sucker to the floor to keep him from getting up and killing us all.

Seen it, done it, doing it tomorrow, got a closet full of t-shirts.

Be carefull out there...

14 CFR Part 91: General Aviation
Accident occurred Sunday, April 14, 1996 in HARTWOOD, VA
Probable Cause Approval Date: 5/13/1997
Aircraft: Cessna P206C, registration: N8682Z
Injuries: 1 Fatal, 2 Serious, 1 Uninjured.


The pilot stated that after climbing to 10,000' msl on a skydiving flight, the occupants began preparations for the fourth and final parachute jump of the day. The first parachutist (skydiver) of three was standing on the right wing strut preparing to jump, when his main parachute (that he had packed himself) deployed inadvertently. He (and/or his parachute) struck the right horizontal stabilizer; subsequently, the stabilizers (empennage) separated from the airplane. The second skydiver stated that he had one foot on the wheel step and the other foot in the door when the first skydiver's main parachute deployed. He stated that the airplane gyrated and that he was pressed against the lower side of the wing, but he was able to free himself. The pilot stated that shortly after the first skydiver had exited the airplane, he (the pilot) felt a 'thud' and the airplane started to react violently. The pilot tried to regain control of the airplane, but was unsuccessful. He stated that he and the third skydiver were slammed around inside the airplane as it continued gyrating. The pilot exited the airplane by pulling himself to the door. The third skydiver did not exit the airplane, and the airplane crashed. Examination of the wreckage did not disclose any preaccident anomalies. The National Transportation Safety Board determines the probable cause(s) of this accident as follows:

the inadvertent/premature deployment of the first skydiver's parachute, which resulted in contact with the airplane's horizontal stabilizer by the first skydiver and his parachute, loss of integrity of the empennage to the aft fuselage, loss of aircraft control, and subsequent separation of the empennage. The third skydiver was fatally injured when he failed or was unable to bail out of the uncontrolled airplane.


Full narrative available

 

[FN FAL]

I think there are a lot of books that could be written by people who profess to be experts on shock cooling. I'm sure they'll chime in as soon as possible with unverifiable stories about how they did or saw this and that. I say bunk! Write a book on it and get it published! DZ owners make their bread and butter off of that plane going up and down, not with it sitting in the shop while thousands of dollars a day in business gets turned away.



Giving the "cut" from 17 inches of manifold pressure, to just under 14 inches of manifold pressure, isn't going to shock cool sh!t. About the only thing I can think of being too cool is going to be your carb heat, in the case an engine dies on you during the "cut". And the "cut" is not done abruptly...it's done smoothly.



We run two 182's with the 0-540 conversion engines in them and we just got 1800 hours out of the one engine...it went out with a cracked case, but that was a problem of age, not shock cooling. You can only rebuild something so many times before it goes to the trash bin. And who hasn't replaced jugs on a Cessna? It happens.



We use specific procedures to "pre-cool" the engine before jump run and we use specific procedures for descent. Temperature monitoring of the EGT and CHT is done from take off to landing. And yes, the owner of the DZ doesn't want your monkey ass trashing the plane and he wants it up and down as fast as humanly and mechanically possible. For those of you who never worked at a real job before you got into aviation...it's the same at the factory, the same at the warehouse and it's the same at the fast food joint. They want you to do the job you are paid to do, without trashing anything and while being as productive as possible. Who would have imagined that concept.

If you want a job where there is no pressure to produce, I would look at government careers...specifically in the federal government. You can trash stuff there, maybe even get people killed and not have a care in the world, just ask Janet Reno.

 

[RedheadCFI]

Hey, I can vouge for the black eye flying divers. I swear to god the brake was on, the wheel just happens to spin when a complete as*hole that complains about the last lift w/you steps on it. Here is a tip from one jump pilot to another. Get a copy of the key to the aircraft and take it with you on every flight, and if the last guy out points out traffic at your 7 o'clock don't bother looking.