Bob McDonald's Blog (19)

She Flew Out Of My Life - The Zen

This is "The Zen".

It is a 2005 kit built CH601HD that was built by Trevor Page, and sold to me & Ray Nash in 2007. At the time Ray & I had been flying Quad City Challengers on wheels / skis / amphibian floats. We wanted a faster go further adventure aircraft that was still in the Advanced Ultra Light Aircraft (AULA) category here in Canada. It was also the aircraft that introduced me to Zenair / Zenith kit planes, the Rotax 912 series of engines, and the hopeless addiction of…


Added by Bob McDonald on March 21, 2021 at 5:57am — 6 Comments

Youtube Channel with CH601HD & CH701 + others "Grass Roots" flying.

Check this YouTube channel out if you enjoy "Grass Roots"  flying videos. Mix of GA aircraft and the CH601HD / CH701 aircraft. CH601HD (both taildragger & tricycle gear) flying skis. They fly in Ontario, Canada.

Added by Bob McDonald on March 13, 2021 at 6:30am — 3 Comments

Because I'm A Pilot - "Bob's Okay"

I have not posted much in the last few years, preferring to lurk in the internet shadows and follow the adventures of others. I still answer questions quickly in PM sent through the web site. The 2005 CH601HD rests quietly in the hangar its systems "mothballed"..... ignored the past 2 years. Like an unfaithful boy friend my fancy had turned to another aircraft. A 1976 Citabria GCBC a friend with too many aircraft was generous enough to loan me. I learned to handle the evil "tail wheel" gear,…


Added by Bob McDonald on February 5, 2020 at 1:27pm — 12 Comments

How To Lift CH601HD To Change Main Gear Bungee

Bungee have a 5 years replacement life cycle based on the color code on the bungee. The CH601HD has a nose gear bungee, and 2 bungee / main gear. All bungee 1080HD. Other builders have asked me how I replace main gear bungee. Pictures are worth a thousand words... and I hate typing.…


Added by Bob McDonald on November 11, 2019 at 9:34pm — 1 Comment

Old Style Trigear Amphib Floats" />

Does anyone have a set of the older style CH701 / CH601HD Zenith / CZAW floats?

I'm bored these days without a project, so I'm thinking my CH601HD would be cool to fly on floats. Anyone have a drawing for the front steerable nose gear. If I remember these were compressed air…


Added by Bob McDonald on March 4, 2016 at 10:23am — 5 Comments

Flygas - Rotax 912 SUPERCHARGER = 140 HP

Here is a real product to wake up your Rotax 912 80 hp engine.

Failure of the Supercharger simply means you have to fly on the original 80 hp.

Added by Bob McDonald on January 29, 2015 at 3:25pm — 6 Comments

Bob McDonald Is Alive & Well :>)

Thank you for your concern... I am alive and still kicking :>)
I kind of stepped away from all my normal activities (except work) last October when my father "Robert Bruce McDonald" was diagnosed with ALS (Lou Gerhig's) disease.
At 85 yrs. the progression of this disease was very rapid. He was unable to walk after Jan.2014, and almost totally paralyzed and unable to speak by May 2014. He passed away June 07, 2014 aged 86 yrs.
His only request was to stay…

Added by Bob McDonald on July 14, 2014 at 3:29pm — 16 Comments


Here is a gently used Rotax 912 80 hp for sale.

I know the owner and aircraft history. Its good.

The Rotax 912 80 hp is great engine for the CH701 or CH601HD series aircraft. I have flown both models with the 80 hp Rotax and they fly great.



Added by Bob McDonald on August 18, 2013 at 10:18pm — No Comments

C-IMPH First Flight

First flight of Mac McCullock's CH750 registered AULA in Canada. Rotax 912S engine. Mac did a days CH750 type training with me prior to 1st flight.

Added by Bob McDonald on August 12, 2013 at 11:04am — 3 Comments

How difficult Are Zenith Floats To Build?

Since posting pictures on this site I have had lots of requests for information, and pictures of my 1450 Amphib. float build.

Zenair has an instructional web page set up just for this purpose.http:// . It is sort of hidden away unless you are looking for it. Go to this page and look over the instructions for both the "parts kit" and "pre-drilled kit". You will notice the…


Added by Bob McDonald on June 23, 2011 at 3:46pm — 3 Comments

Hand Pump Floats or Electric Pump

When you order Zenith amphibian floats you have to chose between operating your retractable wheels either by a hand pump or electric pump. Zenith does not price either pump differently...but if you want a hand pump to back up the electric version its an additional $1000. The hand pump must be mounted between the pilots legs so it can be operated by the pilot. The electric pump can be mounted in the rear and operated with a single switch. Both pumps weigh the same. Do any of the builders have… Continue

Added by Bob McDonald on May 13, 2011 at 4:41pm — 7 Comments

Leaking CH701 / CH750 / CH801 tires

I think most builders have at least one slow leak tire on their aircraft. On mine its the nose gear tire, it leaks down over a couple weeks while the mains have never leaked. I was thinking about putting tubes in the tires, but that adds extra cost and weight (I assume that is why tubes are not included in the kit?). A fellow builder Bob Stuart (CH701 plans only) suggested removing the valve stem and injecting (syringe) 5 - 10 cc of anti-freeze then installing the stem and inflating the…


Added by Bob McDonald on May 5, 2011 at 4:13pm — 10 Comments

Rotax 912 Honeywell Oil Pressure Sender

My CH750 is powered by the Rotax 912S engine. To date I have 90 trouble free hours on the engine with no adjustments required other than tightening a radiator hose clamp. While flying the other day the engine oil pressure started to fluctuate and go full scale both directions on the D180. This really gets your attention! I selected a field for a forced landing, but after flying the approach with Rotax humming along happily (all oil temps & cylinder temps normal) I reasoned I was risking…


Added by Bob McDonald on April 13, 2011 at 7:43am — 12 Comments

What Ever Happened To The Zodiac Gemini CH620?

A question for all the Zenith builder & fans out there..."What ever became of the Zodiac Gemini CH620?"

I have the factory information about the aircraft it. I stumbled across the literature while going through a stack of aircraft sales pitches I collected over the years. For those of you who have never heard of this aircraft it looked like a it was a version of the CH601HDS series, with retractable tri-gear and twin Rotax 912 80 hp engines on a low wing. It was a two seat…


Added by Bob McDonald on November 18, 2010 at 9:30pm — 8 Comments

CH750 / CH701 Gas Caps

I have gas caps that leak when I go flying. This is evident by the fuel streaks down the top of wings from the filler necks after I land. I suspect this is from the position of the filler neck & fuel caps is steep turns. High wing tank leaks in a turn. I also noticed that the right fuel tank level was always higher than the left after going flying.

The tanks would start out level if left in the hangar over night. I went to dip the tanks after flying and heard a "whoosh" upon…


Added by Bob McDonald on July 28, 2010 at 8:17pm — 10 Comments

Another Day At Can-Zac

Remember the CH750 kit owned by Angus Watt from Ottawa, the one I spent 8 days working on last month? Well, at the end of 4 weeks it looks like this... by the end of this day the wings and all flying surfaces are final fitted and it is once again dis-assembled and shipped to the paint shop today.
The CH801 (Yellow/Blue?White paint)in the back ground is a 4 seat model built for an outpost camp in Alberta.

Added by Bob McDonald on November 17, 2009 at 6:59am — 2 Comments

CH701 & CH750 Wheel Skis

I heard a rumour that Zenair was going to release plans / kits for wheel skis to fit the CH701 & CH750 model aircraft. I thought it would be a wonderful early Christmas present (project) for the model owners from Zenith (Chris Hientz).

O.K. I will admit to starting the rumour ! I saw a wonderful looking set on a CH701 owned by Rob Nelson on the completions section of the Zenair web site. Winter comes early here in Canada and wheel skis would be a ray of sunshine in my part of the… Continue

Added by Bob McDonald on October 30, 2009 at 1:20pm — 9 Comments


I was offered a chance to be part of a 3 man (sometimes 4) team conducting a CAN-ZAC Power Build program. The kit owner Angus Watt from Ottawa started with Mark Townsend building from a 6ft X 6ft X 12ft crate Friday, and I joined them on Monday afternoon. Neither Angus or myself had any previous kit building experience... but we were closely supervised by Mark Townsend of Can-Zac in his Kitchener hangar. The working day starts at 8AM (or earlier if you can't sleep) and generally goes hard until… Continue

Added by Bob McDonald on October 27, 2009 at 8:19am — 5 Comments

CH601HD Bungee & Gear Leg Replacement

Well... Yesterday I started into job on the CH601HD that is very much like force feeding a Porcupine to a Grizzly Bear ! I used an ATV jack to lift The Zen, there is no weight the wings... its a "Plan B" thing. Grantley Este & Bob "Mr. GoodWrench" Braden pitched in to get me started on the job I have been putting off for a year now. Changing the out of date main gear bungee (5 yr replacement cycle), so far it has taken 3 guys the better part of a day to jack up the aircraft and get the gear… Continue

Added by Bob McDonald on June 26, 2009 at 7:44pm — 1 Comment

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