Problem on first x-country

[Jamie]

Flew from HSV->CGI  (Cape Girardeau, MO) yesterday to see the family. Great trip. The autopilot gave me time to really get to know the engine instruments and engine monitor, which is why the trip back was aborted.

 

Short version: The fuel pressure and oil pressure panel meters were seemingly stuck on "max pressure" (red).

 

I noticed this on take off, but since I don't know the airplane well yet assumed it was normal on full throttle take off. So I climbed a few thousand then leveled off and throttled back to 20" or so. Still redlined. That's when I decided to return to the field. The other engine instruments were green, and the engine monitor didn't show anything unusual. It was only when I throttled back to idle just before landing and during taxi that the pressure indications came off red line back into the green.

 

Stuff that may or may not be related:

 

* When I started up for that flight, the engine monitor was "going nuts". Blinking randomly (not in a test pattern as far as I could tell, more like an electrical / software bug).  I shut the master off, waited a few seconds, then turn it back on and the engine monitor was fine. This, with the engine running.

 

* Turning the fuel boost pump on/off made no difference in indication.

 

* New battery (concorde) installed (and test flew) earlier this week.

 

* Normal fuel flow according to the totallizer.

 

I'm stuck in Missouri with the parents until at least Monday when the local A&P can take a look. Suggestions for what to look at?

[N201MKTurbo]

Those gauges are electric in the 81 J. I suspect there is a connector issue.

[FloridaMan]

I am not an A&P, am nothing more than a rank amateur, nor have I stayed at Holiday Inn Express in years, but I have a couple things that I've noticed that may help relieve you while you wait for a professional's opinion. 

 

On my 67F I believe the fuel pressure gauge indication is in the fuel system before the fuel distributor and always sits at red line, except when I've run a tank dry, then it drops off a few seconds before the engine quits. As I understand it, Lycoming has no upward limitation on oil pressure on climbout and max power settings. I was alarmed once in a rental for the same reason. Also, Byron posted a thread regarding higher oil pressures on his remanufactured engine. I've heard that the pumps are not capable of creating "too much" oil pressure for those engines. 

[bd32322]

Since these gauges are on the top, it should be easy to take the glareshield off and check the connectors like N201MKTurbo mentions

[M016576]

What type of engine monitor do you have that was "going nuts"? Id check the ground on the ships gauges- mine came loose on my 80J once and it caused some similar problems.

[Jamie]

What type of engine monitor do you have that was "going nuts"? Id check the ground on the ships gauges- mine came loose on my 80J once and it caused some similar problems.

 

It's a GEM 602. I guess the best way to describe what I saw is what happens to a microcontroller when it starts up undervoltage. I mean, it depends on the program it's running of course, but it looked like it was trying to run with the bench power supply turned to too low of a voltage / current.  It wasn't on a seperate breaker that I could see, so I turned off the avionics master, then turned off the main master (I left the engine running). Left it off for a count of 5 or so, then turned it back on. The engine monitor seemed fine after that.

 

Runup went fine, nothing unusual on takeoff, climbout was fine. I mean, if I hadn't just spent 1.5 hours staring at those guages, I would have just headed on home. But the max indication was unusual.

[Marauder]

Jamie - I have a GEM 602. If your GEM is connected to the master and you do not have it connected to the avionics masters, it may do what you are describing, a transient spike or low voltage causing an erratic display. I have mine connected to the avionics master as recommended in the installation manual. My oil pressure always is on the high end of the scale, but not redline. Been this way for the 22 years I have owned her. You mention a fuel flow monitor. Do have a pressure sensor on this unit? My factory fuel pressure gauge is mechanical (fuel is sent to the gauge), but it matches the EI fuel totalizer's pressure.

[Jamie]

No. At least I don't think so. It's a Hoskins FT-101. It seems to only show current gal/min and total used.

 

Thanks, everyone. Hopefully they can look at this tomorrow morning and it's something simple. I'd be happy if they could rule out an engine problem and I fly it home. Dealing with it away from home sucks.

[FloridaMan]

For what it's worth, on my first x/c in my airplane which was right out of annual, I stopped in the middle of nowhere in TN for cheap fuel on my way back to FL. Ended up with a dead magneto on a saturday in a town with no hotel, no taxis and no rental cars with a pilot doing my checkout with me. I had to charter a limo from Nashville, get two hotel rooms and two airline tickets back to Tampa, get the magneto fixed and return to TN to pick it up. 

[FBCK]

I have an EI UBG-16 and it started to do the same thing about two weeks ago.  I call EI, great people I might add, and the gent told me some of the older instruments can do this a low voltages (he was taking abouy 8 volts or so) or as suggested above it is a ground issue each external to the device or internal.. Suggest ucking it up to an external 12 volt to determein if it is ext or internal ground issue, which I haven't done yet.

[Hank]

For what it's worth, on my first x/c in my airplane which was right out of annual, I stopped in the middle of nowhere in TN for cheap fuel on my way back to FL. Ended up with a dead magneto on a saturday in a town with no hotel, no taxis and no rental cars with a pilot doing my checkout with me. I had to charter a limo from Nashville, get two hotel rooms and two airline tickets back to Tampa, get the magneto fixed and return to TN to pick it up.

But you and Parker had a good learning experience . . . . :-)

[FlyDave]

On the fuel pressure - I have had the same issue numerous times and it's always been the connection the the fuel pressure sending unit has become loose. In fact, I need to take my cowling off  now and fix that after a shop did some repairs and "cleaned the engine" with a high pressure solvent spray.

I also had a Gem 602 and experienced the same thing you did. I was told by Insight (manufacturer) that it must be grounded to the engine - not the airframe. But cycling power on the Master would take care of it when it happened. I've since replaced the GEM with a JPI 830 and am happier with the JPI.

[Parker_Woodruff]

But you and Parker had a good learning experience . . . . :-)

 

Just don't break down in Smithville, TN.  The A&P is a good guy though.  And it's pretty.  Unless you're standing at that gas station/motel combo.

[FloridaMan]

Just don't break down in Smithville, TN.  The A&P is a good guy though.  And it's pretty.  Unless you're standing at that gas station/motel combo.

 

I'd go so far to say that if you are gonna break down, Smithville is a good place for it because of the A&P. Of all the relatively slow small town airports that are out there, I think we were extremely lucky that it happened there and that the weather was nice, and that it wasn't the next weekend, which was Bonaroo outside of Nashville. We would have been extremely screwed in that case considering all flights were booked and transportation would have been impossible to come by.