RNAV Approaches with a Portable GPS

As I mentioned in my other blog, last Fall I was forced to fly a RNAV (GPS) approach into Lynchburg with a portable GPS when the ceilings dropped faster than forecasted.  We managed ok but it was definitely a nail biter since my portable GPS is not approved for IFR approaches.

Since that time, I've been researching upgrading DKX for true IFR capabilities and I've concluded that the high cost of approved navigators is simply out of the question.  For example, the cost of a Garmin GTN 650 navigator is $11K US plus installation. When you add in the related other equipment--antennae, CDI, etc., the cost is well north of $17-18K Canadian.  That's nuts.  Almost 1/3 the cost of the airplane!

And considering that Garmin's Aera 660 Portable GPS (which is what I have) at $700 US contains many of the same features as the GTN650 , it's incredibly hard to justify the expense when you fly approaches so infrequently.

It certainly shows how TSO (Technical Service Order) requirements that the manufacturers must go through to certify their equipment really drives up the costs.

So until I upgrade for ADS-B next year, I'm going to stick to the status quo.

So having said all that, I've been looking how I can optimize the use of my portable GPS.  Technically, a non-certified GPS cannot be used for primary navigation on an IFR flight plan.  As I've mentioned before, DKX is legal for IFR but my equipment is in the same league as "stone knives and bearskins", to quote Mr. Spock.  So while I should legally be filing and flying the airways (using VOR's), no one does that anymore.  I mean no one.  Everybody goes "Direct" and ATC expects that virtually everyone can do that.  The only way that's possible is with RNAV equipment (which is short for Area Navigation) and that means GPS 99% of the time.  (Inertial Navigation is another, but that's limited to commercial jets).

So the fact that I'm using a portable GPS for enroute navigation, i.e., going direct, is not really kosher, but it's ok in my mind because a) I'm always in a radar environment so if you somehow got off course, ATC will notice and call you, b) I have Foreflight running as a GPS backup and c) the portable aviation GPS navigators are incredibly reliable.  I've had 4 or 5 over the years and never had a malfunction.  And even if one blew up in the air, I can always revert back to flying the airways using my NAV/COM radio and VOR's.

Approaches, of course, are a different story.  Nowadays, most GPS are WAAS (Wide Area Augmented System) capable and their accuracy is phenomenal.  And as you get closer to the ground, that accuracy is important.  My portable is WAAS capable too, but it doesn't really make a big difference since it won't let you navigate a profile below 1500 ft or so.  It has a cutoff feature that prevents idiots, like me, from using it for vertical guidance as you get close to the ground.

So how to fly an approach, albeit quasi illegally, but in a quasi emergency, using a portable?  Here's how to do it.

First, you must have a digital autopilot (like a TruTrak Vizion) coupled to the GPS.  Trying to hand fly the airplane while you force fit a portable to fly an approach is a recipe for disaster.  The workload is just too high.

Second, you must have personal minimums.  In the majority of cases, the ceiling can't be below 1000 feet, so the field is legally VFR (and the manoever is essentially cloud breaking).  That way, if your busted by Transport Canada or the FAA, you could argue that you were VFR the whole time.  Yes, illegally flying an IFR approach but not really compromising safety.

If legality is not an issue for you, and you're pretty confident in your ability, I would descend to circling minimums.  That way you can still manouever in the vicinity of the airport if something goes south at the last minute.

In a real emergency, I would fly right down to the LNAV mins.  I've done this many times practicing at my home field and it's perfectly safe.  Let me explain.

The Garmin 660 (and the other Aera series portables) come loaded with instrument approaches for every airport in North America.  Amazing.  Now, they are there for "monitoring" purposes only, and are not to be used to fly an IFR approach as primary navigation.  Never.  Not ever.  Ever.

To ensure that idiots, like me, are not tempted to do so, only the approach segment from the Final Approach Fix (FAF) to the Missed Approach Point (MAP) are included.  If you load and activate an approach, the GPS immediately provides course guidance direct to the FAF (and if coupled to the autopilot, the plane immediately turns towards the fix which is not helpful.)

The obvious solution, is to augment the approach with the missing waypoints, i.e., the IF (Intermediate Fix) and the IAF (the Initial Approach Fix).  Amazingly, these too are included in the GPS database (although not part of the approach...yet).

By retrieving the needed waypoints from the database, you avoid the big no-no of creating your own user defined waypoints and screwing things up.  It was this specific issue (creating your own waypoints) that made everyone very nervous when GPS's first came out.  And rightly so.  Real idiots (worse than me), created their own approaches from scratch and occasionaly flew into solid objects when the waypoint was in the wrong place.  Very poor form.

So the technique is a follows.  Note that the autopilot flys the plane the whole time.  No hand flying at all.

While enroute, and when you know what approach to expect, append the missing waypoints to the flight plan.  But make sure the plane keeps flying to the destination, until your cleared for the approach.

Once cleared, and directed to the IAF, go direct to the IAF using the autopilot.  While enroute, activate the approach BUT you must do this when the autopilot is in Heading mode (and not GPS NAV mode), or else the plane will prematurely turn to the FAF.  Once the approach is activated, redirect the plane to the IAF and reengage the GPS NAV mode.

Voila!  The plane will fly the full approach, sequencing throught the waypoints just like a certified unit.  You fly the profile using the Vertical Speed and the Altitude Select knob.

Once final point.  If you need to make a 90 degree turn at the IF (like most RNAV "T" configurations) you can't let the autopilot do this directly.  Without GPSS steering, i.e., turn anticipation (which the certified units have), the plane will overfly the waypoint before it turns to intercept the next leg, usually at a 45 degree angle.  This maybe ok enroute but doesn't work on an approach.

The solution is to briefly put the autopilot in Heading mode, anticipate the turn by 30 sec or so (remember a rate one turn is 3 degrees per sec, so 30 sec for a 90 degree turn) and use the heading bug to turn the plane.  As it approaches the final approach course, re-engage the GPS NAV mode and the autopilot will quickly recapture the inbound course and fly the plane right to the runway.

Piece of cake.  Fly safe. 

The Annual Inspection and The Bad Magneto

Let's cut to the chase.  The bill for my last annual inspection was $1800.  Yes, it was a bit of a shocker since I was used to paying less than half that amount.

The unexpected issue that came up had to do with a bad magneto that was discovered after the annual was complete.  The bill for repair, including re and re was around $600.  So the annual ran about $1200 which was what I was expecting now that I was using a new AME at Edenvale.  But I could not help but sigh--the halcyon days of cheap annuals were now long gone.

Here's what happened:

Once the annual was complete, we pushed the plane outside and I did a run up.  Everything seemed to be working ok, including the mag drop for both mags--less than 50 rpm for each.  The magneto timing is checked at each annual so its important to validate each mag is working ok before you go flying.

As I was shutting down, I checked the mags at idle speed of 1000 rpm just to make sure everything was ok.  Usually, you get an rpm drop but the engine contines to run, albeit a bit roughly on the active mag.  The left mag was fine, but when I isolated the right mag, the engine died right out.  Which was a bit puzzling.  I ran them up again at 1700 rpm.  Both were fine.  But at 1000 rpm, the engine continued to run on the left, but wouldn't on the right.

I shut down and had a chat with Chris.  He said it was probably a fouled plug.  We didn't have time to pull things apart that late in the day, but he said he would come over to my hangar the next time I was on the field and have a look.  I said ok, but was a bit unhappy in that I am perfectly capable of checking the spark plugs myself but with Chris doing it, the meter was running at $85/hour.  But since it was still part of the annual, I figured it was better letting Chris do the work.

The next day we met at my hangar.  I  fired up the plane with the cowl off and Chris went around and tested the heat coming off each cylinder exhaust with a special tester.  If a plug is fouled, the temp of the offending exhaust is usually lower.  That way, you don't have to pull all 8 spark plugs out and test each one.  But they were all ok (which made sense since we had cleaned and gapped them during the annual)

Chris then thought it might be a bad ignition lead (which we didn't test during the annual as there is usually no need).  So I taxied the plane over to his hangar and he tested all the leads--no joy.  They were all fine.  We scratched our heads and decided to pull all the plugs anyway, just to make sure they were ok. We did and they were.

Therefore, by simple deduction, it had to be the magneto since the other components of the ignition system were ok.  So Chris pulled the mag and we arranged to have it sent to an overhaul shop in Orillia.  Just to make sure, he had a spare mag in his shop, so he installed that, timed it up and I did a runup.  It worked perfectly, no engine cut out on the right side.  So it was nice to have the confirmation that we were on the right track.  And I could still use the plane while the mag was being repaired.

A few days later, I flew to Orillia to pick up the overhauled mag.  The tech had found a burned out condenser (I think it was), replaced it and it was good to go.  $475 worth of good to go.  Ouch!

Chris had it installed on the plane the same day and took back his loaner mag.  We updated the logbooks and the annual was finally complete.

Looking back on the process, I had a few observations.

First, the magnetos had about 500 hours on them.  They were installed new with the major engine overhaul done a couple of years ago.  Slick, the manufacturer recommends the mags be overhauled every 500 hours.  Yeah, I can see why.  On the other hand, many mechanics say there is no need to overhaul the mags that frequently.  The argument is since there are two, even if one fails in flight, you can still get home.  My old mechanic Frank said he had seen mags run to TBO or 2000 hours on some engines.  Maybe they don't make them like they used to.

My sense, after overhauling quite a few mags over the years, is to do them at 750 hours.  That's when I'll do the left one.

My second observation:  while the inspection was generally as advertised, I was not all that surprised that something came up that wasn't expected.  It's complicated machinery.  Stuff happens.  Still, after 26 years of doing annuals, I've found that most are a non-event, especially if the small stuff is being looked after throughout the year and you keep a careful eye on things.  But looking back, it seems that about every 4 years or so, you hit a big one that's requires more $$.  Hopefully, not $$$$$$.

To this point, other than 2 scheduled engine overhauls in over 5000 hours of flying, I've never had the dreaded big one.  Hopefully, never will.

The Annual Inspection--Are You Sitting Down?

Privately registered light aircraft are required by Transport Canada to be inspected once a year, independent of hours flown.  Commercial aircraft on the other hand, must follow a prescribed maintenance schedule that is based on hours flown, usually every 25 or 50 hours.

DKX is owned by me and is, of course, privately registered.  Its annual inspection is due every Spring usually in May.  For many years, I had the good fortune of using a local AME (Aircraft Maintenance Engineer) who had a full time job working at Navistar in Chatham, but worked on little planes in his spare time.  Again, when I worked at Seneca College in Peterborough, I used an AME who worked at the college during the day and fixed little airplanes on the week-end.

The advantage of using both these guys was they were cheap.  Not that they did poor work, but that their primary source of income was met by other means and they weren't motivated to charge an arm and a leg for work they did on the side.  For example, Frank, my AME in Chatham, charged a flat $700 for a no snag inspection.  Chris, my guy in Peterborough, charged $400 for an owner assisted annual.  I usually gave him $500.  Regrettably, both these guys are now dead.  Which sounds a little harsh, but the cool thing with Chris, who died of stomach cancer a year ago, was I had the privilege of leading him to the Lord before he died.  That was truly cool.

When I moved the plane to Edenvale, I naturally decided to use the mechanic located on the field, who is also named Chris.  He seemed like a nice guy and was well spoken of by many of the other airplane owners on the field.  He agreed to do my annual inspection, in his hangar at Edenvale, last May.

As I mentioned before, I do a lot of maintenance on the plane myself, having learned quite a lot working with mechanics over the last 26 years. Over time, I was able to earn both Frank's and the first Chris' confidence such that they were willing to let me do a number of tasks myself.  They would then sign off the log book after inspecting the work.  Over time, they stopped inspecting and simply signed.  It was a great deal and I was very grateful to have earned their trust.

Now I had to work with a new guy and that was a big unknown.  AME's are generally very wary of know-it-all pilots, particularly those who profess to know anything more than the standard systems knowledge that is required to get a pilot's licence.  Often, they know just enough to be dangerous.  It's true.  I've known a few of them.  As a result, AME's believe that a pilot should stick to flying the plane and the AME should stick to fixing them.

Fortunately for pilots and wannbe AME's like me, Transport Canada comes to the rescue.  Transport insists that the aircraft owner is ultimately responsible for the maintenance of his or her aircraft.  I know that sounds weird, but it makes sense when you think about.  If an aircraft crashes, whom do you blame?  You might say, well, if the pilot bends the plane during a crosswind landing for example, then it's poor pilot technique and he's to blame.  If, on the other hand, a plane takes off with the aileron cables installed backward (don't laugh, it's happened) and crashes, then it's obviously the AME's fault.

But what happens if the vacuum pump fails (due to poor maintenance), the vacuum driven instruments fail (because of the pump) and the pilot loses control of the plane (because of poor partial panel technique) and the plane crashes.  Now, whose fault is it?  Well, it's both.  But to what degree?  And therein lies the rub.  Insurance companies (and the Transportation Safely Board who investigate crashes) like to have a primary guilty party to go after.  And if the pilot is ultimately responsible for everything to do with the flight, then he's the guy.  That's why the term Pilot Error comes up in 90% of aircraft crashes.

But you might say, wait a minute, a pilot can't be responsible for crossed aileron cables!  Yes, he can, because a proper pre-flight inspection should check for free and correct movement of all controls.  What about a broken vacuum pump?  Nope.  All pilots train for partial panel ops for just such an eventuality. 

So other than the rare, big, catastrophic mechanical failures (like a failed connecting rod for example), the pilot is held responsible for just about everything else.

So what has all this to do with a private owner/pilot working with his AME?  Plenty.  The AME knows that if anything goes south during a flight, the pilot, not the AME will be probably in the hot seat.  Therefore, the pilot gets to call the shots.  The AME can make recommedations ("we really ought to swap out this vacuum pump") but if the pilot refuses ("I think it'll last another year"), the AME is in the clear, provided he documents it, i.e., "item deferred by owner". 

Finally, it should be noted that the AME is certainly not powerless.  He has the power to ground an airplane should an item be found not airworthy.  And even if the owner insists it's ok, the AME can stand his ground and refuse to sign off the plane.  It would be a fool who ignored that kind of a warning.

So back to our story.

I had a great chat with Chris.  I explained my desire to do the minor stuff myself, under his supervision of course, but would defer all the airworthiness items to him.  To my immense relief, he agreed with everything I asked for, saying he had a similiar arrangement with several other owners on the field.

So that's what we did.  The inspection took most of a day.  Chris prepared a "snag sheet" of items as he worked through the plane and it's various systems.  Knowing my engineering background, he went out of his way to explain any issues he found and made sure I understood why he had snagged the item.

At the end of the day, we had a list of about a dozen items.  I gave Chris the ok to fix a few of them on the spot, since it made sense as the airplane was partially disassembled anyways.  The balance I would work on throughout the year.  It was perfect.

And the cost of the inspection?  Well, you'll have to read the next installment about the bad magneto, as it should have made the list, but didn't.

Installing an Autopilot--A Revolution in Flying!

I hand flew DKX for over 20 years.  During that time we flew mulitple trips to Virginia (to see my daughter who lives there), Florida and the Bahamas (for vacations).

I was always interested in installing an autopilot to lessen the workload and make long distance flying more relaxing.  Unfortunately, the STEC autopilot that was certified for 172's was a freaking fortune.  Installed cost was $15-20K which was almost half the cost of the airplane.  Clearly, a non-starter for someone on a budget like me.

At Oshkosh two year ago, I learned of a company called TruTrak that had just certified a 2-axis autopilot for C172's.  Cost of the unit was $5000!  After some research, I learned that I could install the unit myself under the supervision of my mechanic.  I called Chris, my AME and he said, yes, he knew about the unit and would be happy to work with me installing it in my plane.  Whoo hoo!  I  was one of the first guys in line to place an order!!

It arrived in September of that year and the installation began!

First task was to install the roll servo in the right wing.  The servo is held in place by two brackets that are bolted to the rear wing spar.  This obviously involved drilling the spar which kind of freaked me out.  But it wasn't that bad.  The installation instructions are excellent.  The autopilot had originally been developed for the home builder market, so they assume you are not an expert AME.

Following the template, I was able to carefully drill the holes for the backets.  The one mistake I made was trying to drill some of the holes from inside the wing (following their instructions) using a right angle air powered drill that I borrowed from my AME.  It was way too awkward and I ended up screwing up one hole!

Fortunately, I was able to move the nutplate on the backet to accomodate my mistake.  After that, I drilled all holes from outside the wing.  I then mounted the servo in the wing quite easily.

The servo connects to the aileron bellcrank using a pushrod.  I really like the use of a pushrod as you don't have to disturb the aileron control cables.

However, you do need to remove the bolt holding the bellcrank to faciliate creating an attach point for the pushrod.  I debated doing that myself in my hangar at Edenvale (where I was doing all the work. My mechanic is 50 miles away in Peterborough).  But I figured if I couldn't get it back together again, I was screwed because I then couldn't fly the plane to Peterborough for his help.

Thank goodness I didn't remove it!  It was crazy hard getting the bolt back in place and I really needed Chris' help.  It's so nice knowing you have an experienced AME as a back-up when you get in trouble!!

Next came the pitch servo which mounts under the instrument panel and actuates directly on the control column, again using a small pushrod.  This bracket had to be attached to the tunnel on the floor of the plane, just aft of the firewall.  There is not a lot of room under the panel of a 172.  It took some awkward attempts to drill the holes and then squeeze the nutplates onto the tunnel.  The secret is to really take your time, use lots of light and clear stuff out of the way to make access as easy as possible.

Once the two servos were installed, the wiring had to be run from under the panel (where the control unit is located in an empty instrument hole) to the servo in the wing.  I did that but left the harness unconnected under the panel.  That would be Chris' job.  There was no way I could make the terminal connections needed to hook up the wiring harness.

Chris also connected the control unit to the pitot/static system.  Again, there was no way I was going to cut into the airspeed and altimeter lines myself.  That task was way beyond my pay grade.

I flew the plane to Chris place and left it there for him to complete the installation.  He had everything hooked up in less than a day.  I had my brother-in-law drive me back out and I made the first flight!!  The a/p worked perfectly!  It was so cool sitting there in straight and level flight and then engaging the a/p for the first time.  Initially, you don't feel anything but the controls seem to stiffen up and then you see them moving very impreceptably keeping the plane s&l.  So cool!!

The TruTrak a/p will easily follow a course driven by a handheld GPS so we connected it to my Garmin Aera 660 GPS which is mounted on the pilot's control yoke.  It is amazing.  Once a course is set, the unit will follow the waypoints and the altitude hold feature keeps the plane dead level.

Since installation, we have flown the plane to Lynchburg and back several times and to the Bahamas last March.  It has totally transformed my flying, both VFR and IFR, especially IFR.  It's so much more relaxing just sitting there and monitoring everything.

They say that certain technologies revolutionize flying in broad leaps.  The first (in my flying experience) was GPS.  It completely changed cross country navigation.  The second was satellite based weather.  My SiriusXM subscription weather service has literally saved my bacon multiple times.  I simply won't fly without it.

And now, reasonably priced digital autopilots have added a huge measure of comfort and safely to flying little planes.  My wife in particular loves the blue "Level" button.  I tell her that if I have the big one in flight, just push the blue button.  The plane will automatically maintain level flight.  Then push the red transmit button and yell for help.  ATC will take over from there.  (At least that's the theory).  She feels really good about that.

So the a/p installation has been a total success!  I love it and my wife loves it.  It can't get any better than that!!

Introduction to This Blog

My name is Peter Millard and I've owned and operated a 1974 Cessna 172 Skyhawk for 26 years.  Quite regularly, people ask me questions about operating and maintaining a C172.  How much does it cost?  How often is maintenance needed?  What has to be done?  What can you do yourself?

This blog is an attempt to answer some of those questions.  The goal is post stories about maintenance and repairs that have been performed on my plane C-GDKX.  Hopefully, some of the lessons learned by me in both watching and performing maintenance will be useful to others.

I'm a mechanical engineer by education and I've always loved working on mechanical stuff.  My dad was a Rolls Royce trained car mechanic (and an RAF pilot) and I guess I picked up my love of both flying and fine machinery from him.

There's a joke amongst AME's (Aircraft Maintenance Engineers) that asks: "What is the most dangerous thing in aviation?  Answer:  A pilot with a toolbox."

Well I guess I'm that guy.  Thankfully, I haven't done any damage to persons or equipment over the years, but I've been able to save a lot of money working on the airplane myself.

So here we go.  Whether you're a pilot, an aircraft owner, a wannabe or just curious, I  hope you enjoy this blog.