Eric McCandless

Hi Eric,I have my passenger endorsement now and I am doing my second and hopefully 3rd nav tomorrow. First one is with an instructor second one hopefully solo. I am trying to get my navs done by Christmas.

Thanks everyone for your encouragement. The last couple of write-ups were a bit rushed and rough as a result, but I wanted to get them out there. I am severely time constrained at present, but intend to go back and clean them up a bit. I hope they are of use or entertaining to readers. I decided I would present my experiences warts and all (the good and the bad).

Today I completed my first solo nav and it was fantastic. Reasonably simple from Goulburn to Cowra return, but I had a ball and didn't manage to get lost. I also had the pleasure afterwards to hitch a back seat ride in a Warrior with another student doing his second dual nav from Goulburn to Canberra to Wagga Wagga, back to Goulburn. I followed the plan and located position on the chart as we went, so much easier when you don't have to steer at the same time.

Then I burned heaps more circuits and I think it is starting to come together, well until I mess it up as I am sure I will. Next week I am scheduled to do a second solo nav to unknown parts, my instructor has not told me where yet.

I live in Canberra and fly RA from Goulburn. I have yet to complete my Nav and pax endorsements. I have my first solo nav tomorrow (Goulburn to Cowra return). I am really looking forward to it.

Latest Update

Solo Practice Session – Mini-Navigation Exercise – 18 Nov 2012 - (1.7 hours – Total 59.2 hours)

The forecast for today was clear with light winds. Whilst I had flown yesterday for over 4 hours, I decided I should make hay whilst the sun shines and go flying again today. But I wanted to do something different other than circuits and training area. With my pilot certificate I don’t yet have my navigation endorsement, so I am restricted to 25 nautical miles from the airport. However this is actually quite a big area. Indeed it would be quite possible to get lost within this area unless careful preparation is taken. As I have been learning navigation and completed two dual navigation exercises, I thought I might go on a mini navigation exercise, but obviously I must stay within the 25 NM boundary. ............................

I recall hearing a story once of a jab cap being put on with the vents facing backwards, and the fuel being sucked out by venturi force. Does that seem possible, or just a myth?

I think there is a design issue with the Jabiru fuel cap that may cause the cap to leak or come loose in flight, and I am surprised there is not a service bulletin on it. It has happened a couple of times with me in the short time I have owned my J170, until I realised what was happening.

If the Allen nut is loosened too much (more than a couple of turns), the small o-ring between the bottom and upper plates can become dislodged from its locating groove. It is not noticeable until you re-tighten the Allen nut. With the o-ring out of its groove, tightening the nut will result in the cap not seating properly in the tank and may leak or worse, come loose in flight.

I would recommend to never undo the Allen nut more than a few turns and always check that the cap fits flat and firm when tightened again. There should be no movement of the cap in its seat after it is secured with the Allen key. I always gently grab hold of the vent and give it a gentle shake to make sure it is firm. If it moves, then undo it and check that the inner o-ring is properly seated in its groove before re-tightening.

Have others noticed this?

Latest Update

Solo Flight - Practice Circuits and Training Area – 27 Oct 2012 - (6.4 hours – Total 53.3 hours)

"I am in flying nirvana after today’s flights. I did a total of 6.4 hours in 4 separate sessions of solo flight. I flew so much that my right arm got tired from operating the Jabiru’s central control column in flight, but I am not complaining at all. ..............."

Flight Training Lesson 50 - Incipient Stalls and First Time Leaving the Nest – 20 Oct 12

16 Oct 2012 - Flight Training Lesson 48 & 49 – 14 Oct 2012 – Jabiru Solo Circuits & High Performance Endorsement

A great read Eric, and congratulations on attaining your certificate.I'm sure many will learn what to expect in their training from what you have written, and the additional comments from wise mentors like Motz

Well done!

I can easily see how you could possibly publish this once done, with very little polish, into something that could very well become a standard reference for anyone at all stages of learning and accomplishment. I'd buy it.

Flight Lesson 47 – 22 Sep 2012 – Second Dual Navigation Exercise (2.4 hours – Total 43.4 hours)

01 Sep 12. My first navigation exercise.

Attached is an updated calculator showing derivation of PH & DH as taught by my instructor.

Density & Pressure Height Calc Rev1.xls

Density & Pressure Height Calc Rev1.xls

Density & Pressure Height Calc Rev1.xls

I'm sorry if this is a silly question that I should already know the answer to.

Assuming the pilot had 1st stage of flap set for takeoff, in the situation he found himself, would it make the situation better or worse if he set 2nd stage of flap whilst trying to get airborne? Presumably you would have more lift, but also more drag.

There are calculators that take into account ALL of the factors . A POH with height and temperature goes most of the way, but that info is not provided for any U/L that I know of..They might consider the service and absolute ceiling of each aircraft at differing weights and then the density altitude would have relevence., but such a chart does not exist.

Without the Humidity it is not the complete picture either.... The only purpose is to work it out and if it comes to a high figure you might have some idea of how poorly your plane will be expected to perform. A gazelle with two onboard at any DA above 4,000' is a bit of waste of time. One has to know the aeroplane they are flying. I think it is worthwhile to do a few calculations to see how big the effect is. Nev

Can I assume that as long as the calculated density height (and pressure height) is less than 10,000 feet, I can take-off at MTOW?

On second thoughts, that I assume it would be the maximum height to maintain level flight only, insufficient to climb. So how can you calculate the impact of PH/DH for safe take-off?

The POH lists take-off distance 475 m, and landing distance 468 m. Would that be at sea level? If at sea level, how can I calculate the revised take-off and landing distance for different PH/DH?

I have put together an excel spreadsheet calculator if anyone wants to use it (at you own risk as I am just a student not an expert).

Density & Pressure Height Calc.xls

Density & Pressure Height Calc.xls

Density & Pressure Height Calc.xls

I hope I have it right? (Edit: no I didn't, I transposed an incorrect value, hopefully correct this time)

+++++++++++++++++++

Density Height

15 - (PH*2/1000) = x = ISA temp at pressure height

OAT - x = y = ISA deviation

DH = PH + (y*120)

Pressure Height

1013.2 -QNH = x = pressure variance

x * 30 = y = pressure height diff

PH = y + elevation

+++++++++++++++

therefore, calc pressure height

1013.2 - 1003 = 10.2

10.2 * 30 = 306

306 + 5000 = 5306 = PH

now calc density height

15-(5306*2/1000) = 4.39

28 - 4.39 = 23.61

DH = 5306 + (23.61 * 120) = 8139.2 feet.

I'm a huge advocate of hiring aircraft. Simple case of amortising the costs of running the aircraft over greater hours means the hourly cost is a lot cheaper. Takes a lot of hours hiring the school's Gazelle at $135/hour to even come close to breaking even on the ownership case. I also believe that a well used aircraft is a safer aircraft in many respects as it's getting more regular servicing and not sitting around rotting.Having seen the running costs of quite a few aircraft over many years and some of the bills that come up from time to time the only rational choice is to hire. If you find yourself a great organisation where the aircraft are treasured by all who fly them then you can achieve a sense of ownership without forking out the big bucks.

The attached chart is based on the following cost estimates.

Non-Cash Costs

Opportunity Cost (6%)

Depreciation (variable based on hrs)

Cash Costs

Registration

Insurance

25 hour Oil & Filter Change (L2)

100 hourly (L2)

200 Hourly (L2)

Engine 500 hour top end overhaul

Engine Sink Fund (1,500 hrs)

Propeller Sink Fund (2,000 hrs)

Maintenance (ADs, tyres, Instruments, Misc)

Hangar hire (month)

Fuel 15L/hr @ $2.10

My understanding is that fuel tanks should be filled after flight to minimise water condensation due to ingress of moisture laden air. The only reference I could find relating to Jabiru is JTM001-1 Aircraft Service Manual section 4.9 FUEL SYSTEM 100-HOURLY which says "The fuel tanks should be filled immediately after flight to lessen condensation of moisture". There is nothing in the POH.

Given:

J170 MTOW = 600kg

less

My aircraft empty weight = 323kg

Baggage (assumed but max is 36kg) = 10kg

full tanks of 135L fuel (0.72kg/L) = 97.2kg.

================================

Max pilot & passenger weight = 169.8kg

================================

I weigh 88 kg, so I cannot have an instructor/passenger more than 81.8 kg with full fuel and a nominal 10 kg baggage. A check of the trim sheet (my aircraft index =67.7) shows that this is within allowable CoG margins.

If I happen to travel regularly with an instructor/passenger greater than 81.8 kg, then I would need to remove fuel before each flight if I always fill the tank. All good, but a real hassle to remove fuel, but that is what I would do (but not sure how at this stage - siphon hose?) to meet the weight limitations.

If I had a J160 with 540 kg MTOW with the same 135 L fuel tanks, I could only have a capacity of 132.8 kg for pilot plus passenger or with my weight, an instructor/passenger of no more than 44.8 kg with full fuel and 10 kg baggage. Alternatively I would need to remove fuel prior to every flight with a passenger weighing more than 44.8 kg, which is most likely with most flying schools for example.

This got me thinking. Do Jabiru J170/160 owners really fill their fuel tanks after every flight and then drain before each flight? Is it really necessary to fill the tanks as long as you do fuel drains to check for water?

P.S. I am in no way suggesting that the weight limit should ever be exceeded by not removing fuel if overweight.

Wooo Hooo ! I passed my RA-Aus Pilot Certificate Test

14 July 12 - Updated current diary on Google docs.

11 Aug 12 - Jabiru J170 Steep Turns, PFLs, and Crosswind Circuits.

Congratulations Compulsion. It's a great feeling isn't it.

Wooo Hooo !

Today I went for my RA-Aus Pilot Certificate test and I passed.

I now have the privilege to fly within 25 nm of the airport by myself.

Thanks to my instructor for her excellent instruction, patience, and for painstakingly instilling the skills to keep me and other aircraft around me as safe as possible. I fully understand however that my learning and skills are just beginning and will continue the rest of my flying life.

I will endeavour to live up to the trust that has granted to me with the award of my pilot certificate.

Soon I move forward to navigation and passenger endorsement.

Thanks OME. That's good advice about the screw holes too. I am trying to learn as much as I can about my toy, and I also want to be as safe as I can.

Thanks everyone. I have not seen Jabiru publish this anywhere, but perhaps I just haven't looked hard enough. It is not in the POH or in their instruction and maintenance manual.

G'day EricJab produced the attached doc ..... This should help you work out the oil levels for each engines and the levels associated with each dip sticks in production.

 

http://www.jabiru.net.au/Service Bulletins/Engine files/Dip Sticks 8A035A0D-1.pdf

 

Cheers

 

Vev