Runup saves the day
Last Sunday it was finally time to take the entire family on a fun outing. We were planning to make a 1 hour flight up to Mariposa (MPI), stay for brunch and then head back before the day heats up and turbulence sets in. The kids were excited and we headed for the airport. I had done all the planning and the briefing called for a picture perfect day. Car seat in the plane and family briefed for their first flight we finally taxi out in N4313G. The KLN94 has the flight plan loaded (I love that GPS...I finally read the entire manual on an 11 hour flight to Japan a few weeks ago. Even though the plane is constantly flown, only 3 flight plans were loaded..amazing). We arrive in the runup area and it's getting crowded. We're not alone and everybody is out there welcoming summer to California. I go through the runup checklist. Trim neutral, indicator lights, 2000 RPM, mags check, alternator, vacuum...wait a minute....alternator...no indication of load...odd...no fault indication on the indicator lights...try the landing light in addition to strobes, no popped circuit, cycle the alternator master switch. Still no load indication. Run up again to 2000RPM just to be sure. Only the slightest perception of movement on the needle. Normally you see a definite spike. This archer has a loadmeter, which lets you know you're drawing current on the alternator. I don't have a volt meter on this plane that tells me what the voltage is on the bus...bummer.... as a 12Volt indication would definitely tell me I'm drawing on the battery while 14 volt would tell me the alternator is producing the desired output. I call the office to check if anyone else reported any issue, but at this time it's clear already...we're not going. I have the family on board...no way. They were just great about having to go back and canceling our plans.
After we pack up we decide to make alternate plans and head for the beach instead. One of the perks of living in California. As we lay on the beach of course at least about a dozen planes and two helicopters (see left) soar by overhead to which my honey says..."look they're rubbing it in". Of course, like everyone I start questioning.."but what if I had turned on the pitot heat. That draws a ton of power. Maybe that would have given me an indication". Make a long story short we had a great day at the beach, spotted a group of 5 sea otters and for the first time saw wales spouting on their migration up the coast. Another reminder to make the best of each day and accept the curveballs we receive. I wouldn't have traded that day for anything...well maybe a flight to Mariposa.
I called the club's office today just to find out and to learn from the experience. Turns out that one of the alternator wires had come loose. It took the club's mechanic about 10 minutes to fix so it will never come loose again, but the connection had at best been intermittent. We very likely would have lost alternator power on this flight. We would have lost several of the instruments including the GPS and radios, but we would have kept on flying. Not an experience I would have wanted with the family on their first flight out. A thorough preflight and a no-go decision saved the day. That's why we train. In retrospect, the experience helped me review the electrical system, gain confidence in my abilities and I still would have called it the correct call even if it had turned out to be nothing.
In the process I found that not everybody is familiar with the concept of a load meter (left) vs. an ammeter (right). So here is a little summary.
Ammeter: There are two types, the charge/discharge and the load. The charge -discharge will remain centered so long as the system output can meet the system demand. Beyond this point the needle will indicate a discharge and use of battery power. The load type of ammeter will begin near zero and rise as more electrical load is put online. The voltage warning light will indicate if the load requirement is beyond the alternator's ability to produce. The load meter reflects the actual electrical load as it is turned on. A load ammeter at zero or discharge is saying that you are using battery power The ammeter is an essential element of any pilot's instrument scan. It should be a part of the pre-takeoff, prelanding, and checkpoint checklists.
A pretty good summary on electrical systems is posted here.
Still in the mood to learn more? Here is a writeup on electrical system failures.
After we pack up we decide to make alternate plans and head for the beach instead. One of the perks of living in California. As we lay on the beach of course at least about a dozen planes and two helicopters (see left) soar by overhead to which my honey says..."look they're rubbing it in". Of course, like everyone I start questioning.."but what if I had turned on the pitot heat. That draws a ton of power. Maybe that would have given me an indication". Make a long story short we had a great day at the beach, spotted a group of 5 sea otters and for the first time saw wales spouting on their migration up the coast. Another reminder to make the best of each day and accept the curveballs we receive. I wouldn't have traded that day for anything...well maybe a flight to Mariposa.I called the club's office today just to find out and to learn from the experience. Turns out that one of the alternator wires had come loose. It took the club's mechanic about 10 minutes to fix so it will never come loose again, but the connection had at best been intermittent. We very likely would have lost alternator power on this flight. We would have lost several of the instruments including the GPS and radios, but we would have kept on flying. Not an experience I would have wanted with the family on their first flight out. A thorough preflight and a no-go decision saved the day. That's why we train. In retrospect, the experience helped me review the electrical system, gain confidence in my abilities and I still would have called it the correct call even if it had turned out to be nothing.
In the process I found that not everybody is familiar with the concept of a load meter (left) vs. an ammeter (right). So here is a little summary.
Ammeter: There are two types, the charge/discharge and the load. The charge -discharge will remain centered so long as the system output can meet the system demand. Beyond this point the needle will indicate a discharge and use of battery power. The load type of ammeter will begin near zero and rise as more electrical load is put online. The voltage warning light will indicate if the load requirement is beyond the alternator's ability to produce. The load meter reflects the actual electrical load as it is turned on. A load ammeter at zero or discharge is saying that you are using battery power The ammeter is an essential element of any pilot's instrument scan. It should be a part of the pre-takeoff, prelanding, and checkpoint checklists.
A pretty good summary on electrical systems is posted here.
Still in the mood to learn more? Here is a writeup on electrical system failures.
posted by Alex Hammer | 12:47 AM
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