totter

There is still sulfur in kerosene based fuels. The sulfur in the fuel, is of course, the root of sulfidations. Its what is found in the air and enviroment that speed up the process, with salt and then chemicals being the worst. The more salt, or direct contact with salt water, and pollutants the quick sulfidation forms and grows.

I would say a large part of it is caused by salt. You don't have to be in direct contact with salt water or spray to collect deposits on the blades. Just being by the coast is enough due to the salt laden air. This is one reason that corrosion is such a big issue in Florida, even if you only have a land plane, because you're never more than 50 miles from the coast. Also, the salt content in the water increases the farther south you go. So the salt content is 10x greater in the Caribbean than here in Canada and Alaska. The rest of the engine corrosion probably comes from pollutants in the air.

Please explain. In my 15 years of working on turbines I have never known this to be a factor. If it was a factor, so much so as being a safety factor, then one would think that Pratt & Whitney would have, at least, issued a Service Information Letter pertaining to this subject to limit their liability. As opposed to a pistion engine the hottest parts of a turbine are never in direct contact with cold air, even at idle in a descent. 100% power is not used for 15 minutes and then directly to 0%. If I were trying to exit from an aircraft and the pilot was using 100%, lets just say Tail Strike. On jump run the engine/s are at a reduced power setting for several minutes (ballpark/sake of argument 3-4 minutes), then pull back to idle for descent. You have to remember that even at idle the engines are at, just over, 50% and still around 500 C on the temps. As far as starts go the only really bad thing about them is that it costs the aircraft owner a percentage of the replacement cost for the life limited items every time the engine is started. Yes, most of the wear and tear on a turbine is from starts, but you're only doing real damage if your starts are above the normal operating range red line. Even here in Alaska where, at sea level, the temperature difference between the engine ITT and ambient can be 750 C. Shock cooling is just not an issue.

51% - 53% is the proper speed for N1 at idle, also refered to as Ng (gas generator) since all the compressor components ( including CT Disk) rotate at the same speed. 46% - 48% is for Min Flow N1 speed. But Min Flow is mainly for for starting purposes and a maintenance setting that ensures that when the plane is at altitude and the pilot pulls the power back to idle the engine does not flame out. To build on what grimmie has posted, on the Single Engine Turbine Otters we operate here in Southeast Alaska we have found will only go about 3000 hours before we need to replace the Pratt & Whitney CT Blades due to corrosion. What is refered to as Sulfidation. Sulfidation happens in all enviroments and can not be prevented, only slowed down in its formation. Some enviroments will excellerate its growth. It is a by producted of burning fuel. Now I stated Pratt & Whitney blades because the OEM blades don't seem to hold up. One of our planes, which has had PMA blades for a while (around 2000 hours) shows no signs of sulfidation at this point. These are coated with Surmalloy J which is a process used after market in the reduction of sulfidation. To Add: We know none of the current particulars for this aircraft. I used to work on 81F when it was operated by its previous owner. At that time the installed engine had around 4000 total time. Its been 5 years since I've last seen it. Back when it was painted White, Blue and Silver. Don't even know if its the same engine.

I hate to say it but the best source for help would be someone with the CAA, or is it JAA in New Zealand. Anyway, it never hurts to give them a call to ask their advice or opinion. As far as the stuff from MHO, I've used the PVC tubing for 24 place and 19 place O2 systems, (Skyvan, T Otter & Caravan). Never had any issues once the bugs were worked out. The biggest was good flow to the rear seats. Ended up using 2 feeds per side, one for the front seats, one for the rear. The problem with the PVC tubing is 1) The FAA is not familiar with it. Remember that MHO does not sell TSOd or approved equipment. Yes, it's good stuff. 2) For a permanent install the FAA likes to see copper tubing. The main reason being that a ridged tube can not be pinched. Was not able to open your attachment. Can you attach another picture and I'll take a look. Sorry, its been 4 years since I've had to set up an O2 system, so I have no pics to supply.

Not so fast! The STC would need to be APPROVED in Canada for him to use it. FAA / Transport Canada STCs don't mix. Before spending any money make sure of this.

I believe that Transport Canada doesn't do Field Approvals anymore. Its my understanding that a previously approved 337 can be used as the Acceptable Data, but it would all have to be resubmitted, evaluated and approved through the STC process. Not impossible, just more time consuming and expensive. If Canada's process is anything like the FAA's then a One Time Serial number specific STC shouldn't be too hard.

Dave; Nice detailed description. You may want to re-think this last part though; There's a show on NGeo Channel called "Alaska Wing Men". You should give it a watch sometime.

This was back in, oh '97ish. Don't think he was a director then. Might of, but don't think so. $99 to jump as many times as you could over the course of a weekend (Sat. - Sun.). A GO AROUND meant lose of money.

I think you answered your own question: The first brave souls of the day are usually the WDIs.

"get the f@&* out or your comin' back down with me!" Heard that more than once at a $99 Jump till you Puke boogie

Don't forget the other factors. 1) Pollution in the air. 2) Exhaust soot is very corrosive. 3) Anything that will help conduct electrical current 4) Even just turning on the aircraft's electrical system will promote corrosion if the aircraft is not properly grounded or bonded.

Well, to this group they would reply; "What kind of rig does he use?"

I would deem it the "ITS NOT GOING TO HAPPEN TO ME" Syndrome. Operators will start pushing things back saying, "I can't afford that now, I'll do it in the fall" or what have you. Fall comes, "Its made it this far, we'll do it next month". From there it just keeps snowballing. "Ive flown on those cables for 7 years, they get looked at every 125 hours, there fine." "Why do I need to do it?" Pretty soon this applies to everything on the aircraft. Ive seen it happen day in and day out. This is one off the reasons that I, and many other mechanics, have gotten out of skydiving aircraft. Lawyers probably will not let him. "No comment till the hearing."

I think Sparky was just trying to make a valid point, even if his math might be a little off. To put it into more perspective, the FAA can fine up to $10,000 per violation per every flight flown. So the fine works out to be around $320.00 per flight or around $80.00 per violation per flight. $664,000/2100/4 So actually, I don't know why people are so up in arms defending Lodi. In reallity his fine could have been $84 million. HE GOT OFF EASY!

Please do not get things mixed up. ALL skydive operators, in the States, operate "ON CONDITION". Remember that "ON CONDITION" means that components have to meet conditions set forth by the manufacture in order to remain in service. (Performance/Operational & inspection requirements). Even ON CONDITION you still have to comply with Life Limited Items. P&W does not prohibit an ON CONDITION program. They just will not Approve one for skydiving operations. In the states this means very little since skydive ops fall under Part 91 and in Part 91 you do not have to comply with the Manufactures recommendations, (i.e. TBOs) Other than that I agree with what you have posted. You can only see 1/3rd of the Elevator and Rudder cables during an inspection. Maybe 3 feet more if you pull up the cargo floor in back.

Please become a Senator, because otherwise your statement means a whole bunch of useless crap. When you start making the rules then you can make comments like that. Bill tried to get around them and got pinched. End of story.

FACT #1 - All the items listed by the FAA, whether a Life Limited item or a Special Inspection (i.e. the corrosion inspection of the wing) are found in PSM 1-6-11, which is the Structural Life Limit Manual for the Twin Otter. MANDATORY COMPLIANCE FACT #2 - Back in the day there were many operators that did not comply with PSM 1-6-11, because it was not part of the Limitations Section of the Maintenance Manual. The Limitations Section is the only part of the Maintenance Manual that is FAA Approved and technically if not listed there it could be deemed RECOMMENDED by the operator. So, what did the FAA do? They issued an Airworthiness Directive, in 2008, that stated that ALL operators MUST comply with the requirements of PSM 1-6-11. The FAA does not take to kindly when someone blatently ignores an AD.

Try contacting the Los Angeles ACO or Denver ACO. The SW at the end of the STC # stands for South West office, so I would believe it would be LA.

I did 4 static lines there also before going to the Herd for my AFF level 1. It was only 20 minutes from home. Didn't know any better, but glad that I had the chance to jump them. My Ground School instructor for AFF at the Herd could not do a proper PLF so I had to show him how.

You can still use this info as long as the install is similiar. If you find that most are unwilling to part with their info, no problems. All you need is their N# and $10. Go On-line, to the FAA Web site, Aircraft Registration. You can order the CD-ROM, for that aircraft, that will have all that info. Fayards records would be the best that I know. All his mods to the 182, 206 were done after 1998 and the 337s have ICA attached to them. The ICAs will have material used for the door, how it was attached and where to the airframe and MOST IMPORTANT, it will have the limitations (i.e. door open speed, door operating speed, etc.). This is important because any 337 approved before 1998 might not have ICAs and this is what the FAA is looking for.

Is it a standard 206, with co-pilot door, or is it a U206, with a cargo door?

You are correct. Improper wording on my part. It is approved for the specific application (aircraft) being modified, it is acceptable for others to use for a similiar application (modification). Not that it makes a difference to the OP, I didn't notice until you mentioned Poland, but the request for an STC would go to the ACO first. If you stick to the Guide lines in the Field Inspector's handbook, there's a chart that shows you when you need just a 337; DER/DAR info; or an STC. If you have Acceptable Data they can't turn you down. What do you think AC43.13 is? Its ACCEPTABLE DATA written by the FAA. If you submit it without any Approved/Acceptable Data then, YES, your sending it to the ACO. You need to come up to Alaska. We've had about two dozen 337 Field Approvals in the last year on our Part 135 aircraft.

Paul Fayard designed one for his 182. It was a 337 Field Approval. No STC. It used the same basic design as a Twin Otter/Caravan roll up door. 182, 185, 206 all have the same basic fuselage shape. As riggerrob suggested; "Leave enough head room." I remember the Fayard door not leaving much in the way of head room. If you had a tall pilot he/she would have to duck every time the door was opened. If you can find out the N# of Fayard's old 182 you can order from the FAA Registration Branch in OK City all the records for that aircraft, (public records). It cost like $10 for a CD-ROM. It will have the 337 for the door. Once you have that you have your Approved Data and your golden for your 337.

True. Forgot that you mentioned that. I had to ask.