Mystery Battery Drain---solved (at last)

[231Pilot]

Just in case any of you have a battery mysteriously go dead within days of a full charge.

I had a new Concord installed in my 201 at the last annual in March.  Everything worked fine for the first few flights, then on a trip to Houston for the NCAA Final Four the battery was stone cold dead when we arrived at Ellington to make our return flight to West Memphis. The master switch was in the off position when I began the pre-flight inspection.  The AI there checked it out, and then gave us a start with his battery through our auxillary power port on the fuselage.  We arrived with a full charge, parked the plane in the hangar, and the battery was dead in two days.

The new battery was replaced, and that battery was dead in two days.  The mechanic could find no reason.  Today, he called me and said it was fixed.  I asked what the problem was and he told me that after spending a few hours checking connections and components for problems and finding none, he noticed a small reflection on the glare shield.  Further investigation revealed that the dome light switch over the door was in the 'low" position where the light would only be visible in a dark area.  That switch is not affected by the master switch, so it continued to drain the battery, even when everything was turned off (I thought).

Heck, I haven't even noticed that switch in the 5.5 years I have owned the plane, much less turned it on intentionally.  Either my wife or I must have accidently bumped it when deplaning in Houston (on April Fool's Day no less) and not seeing any light, never thought it might be on.

Who'd have thought it?

Just a heads up in case any of you have an unexpected battery drain.

[Magnum]

I left the switch on once, too. Of course far away from home at a big airport. Had to pay 80 Euros (US$ 110,-) for the ground power :-(

[RJBrown]

 When flying with small children the switch became part of my procedure while deplaning. Curious minds and small fingers are attracted to unknown switches. I find it absolutely unreasonable that a "Qualified?" mechanic would fail to find it IMMEDIATLY. The sort of thing that a knowledgeable tech should KNOW to check first. WAY to common to over look. If he bills you for his STUPIDITY he is a crook. Even if he was unaware of the switch finding such a draw is EASY. To change the battery just shows that the person working on you plane is a "parts changer" NOT a real Mechanic. I have owned a auto repair shop for 30 years and I fix cars for a living. If one of my techs made such a rookie mistake I would apologise profusely for such ignorance and not let you pay a thing.

[Geoff]

Randy - with service like you describe, when you open your MSC count me in as a customer!!

[231Pilot]

No, he is not charging for the time he spent.

Some of the larger planes he takes care of have interior lights on a timer, specifically to prebent what we had happen.  So if a door is left open, or a dome light is left on, the timer shuts it down after 10 minutes....wish my plane had that.  He admitted to being a little embarrassed about not looking there first.  However, as to his being merely a parts changer and not a real mechanic, the battery was brand new and the problem didn't occur until a week after it was placed.  His first thought (and mine too) was that the only known quantity that had changed was the battery, so he changed it.  Once he saw that the problem persisted, he took care of it, and as stated before, he did not let me pay a cent for the problem (nor did the FBO in Houston charge me anything to look for the problem and start me with their battery).

 

 

[kortopates]

Although I am with Geoff and Randy, this is a very small example why most of have us have learned to take our Mooney's to MSCs or to Mooney savy mechanics that know our planes peculiarities. But except for not knowing to check the obvious when you first returned, he's standing behind his work which is great to hear.

[RJBrown]

Sarcasm aside this specific repair is too simple for words. For it to stump ANY mechanic you must question his diagnostic skills. To bill for more than it SHOULD have taken is theft.

 I have fixed cars first as a mechanic and now running my own business since June 1st 1981. Any car on the road today is MUCH more complicated than any Mooney. If I have a mechanic lost on a job and have to teach them what to do I dont charge the customer for the lesson. My policy is to charge the customer as if the job was done properly from the start. I have found aircraft mechanics to be more parts changers than mechanics. If a book can't tell them what to do they are lost. A simple wiring diagram combined with common sense would tell you what was NOT on the master switch. Dome light and clock are about it. Check those items. Drink a cup of coffee and stop for a smoke break. Now that you have 15 minutes invested. You are done.

 For some reason we as pilots allow ourselves to be charged for "learning" by the mechanics. There is a flat rate manual for auto repairs. The idea is that a specific job is worth a certain amount.  If a rookie takes longer to do the repair the owner shoud not have to pay more. Conversly if a qualified and experianced mechanic can finish the repair more efficiently he shoud be compensated accordingly.

[Shadrach]

Quote: RJBrown

 When flying with small children the switch became part of my procedure while deplaning. Curious minds and small fingers are attracted to unknown switches. I find it absolutely unreasonable that a "Qualified?" mechanic would fail to find it IMMEDIATLY. The sort of thing that a knowledgeable tech should KNOW to check first. WAY to common to over look. If he bills you for his STUPIDITY he is a crook. Even if he was unaware of the switch finding such a draw is EASY. To change the battery just shows that the person working on you plane is a "parts changer" NOT a real Mechanic. I have owned a auto repair shop for 30 years and I fix cars for a living. If one of my techs made such a rookie mistake I would apologise profusely for such ignorance and not let you pay a thing.

[carusoam]

Part of the M20R transition training is the switches that get left on that are not on the main....

Interior light switches can be turned on in the back seats, fronts seats and baggage compartment.

The clock always runs and the fuel flow has a memory that is wired to a switch.

The M20C had no interior lights like these, the clock was a wind-up that lasted 8 days, and 'fuel used' memory was in my head.....

-a-

[kgbpost]

Thats a good lesson. Any type rating oral examinination begins or ends with "what's on the hot battery bus?". Electrical systems on different aircraft can vary in complexity but you always have to know whats 'hot' even with the master 'off'. It generally tends to be the stuff you really need incase of an emergency. On more complex aircraft it includes engine fire extinguishing and detection and emergency exit lighting, but it always includes cabin entry lights and instrument lighting. Mechanincs dont work on airplanes in the pitch dark, but pilots do. Youd better be able to find that switch with your eyes closed if you ever fly night or night/ifr. Flashlights never work when you need them, believe me.

[butchgilbert]

On my M20F there is an inline fuse from the battery to the hot battery bus.  I have pulled the fuse (reinstalled for night flights).  This solves the dome light issue, and I don't really care about the clock.  IMHO.

[thinwing]

Yeah,...that wasnt the mechanics finest hour....two new batteries going dead  after a couple days non use really screams current draw...if he suspected the battery itself all he had to do was disconnect it check if it was holding charge.The later model mooneys attemped to address this problem by mounting two switches at the pilots armrest.One switch arms all the passenger switches so you dont have worry about turning off the rear seat switches,the second lights up only the pilots courtesey light both hi and low...that one will drain the battery in a couple days since it is 3 to 5oo milliamp draw...the light in the baggage area is on a timer and self extinguishes in about 30 seconds.I would have still paid the mechanic something...he at least made the attempt and chalked it up to my own dumb moment for leaving the light on..kpc

[jlunseth]

I made checking the interior lights one of the last items on my checklist after engine shutdown and before leaving the aircraft.  It is nice, when getting into or leaving the plane in the winter, to be able to get a little light, but having the light switch work regardless of the Master has its dangers also.

[Piloto]

On the later Mooneys after 1990 the overhead cabin lights turn off themself after several minutes if there is no charging voltage.

José

 

[fantom]

Quote: Piloto

On the later Mooneys after 1990 the overhead cabin lights turn off themself after several minutes if there is no charging voltage.

José

 

[Alan Fox]

Randy I also have a shop , working on cars , and a common problem with repairs is that people overthink EVERYTHING.....K.I.S.S.    Keep It Simple Stupid......  You do have to throw him a bone though....  He did admit it was his fault , and he did not charge for the wasted time...     Every once in a while though I too make the mistake of overthinking the problem...  Its a shame they dont have Alldata for planes...

[Clarence]

Hi Randy,

I'm sure that there is not a "flat rate" book for 30,40 & 50 year old cars, if there is I doubt anyone could make much of a living flat rating them. 

I can flat rate work on a newer Aclaim, Cirrus or Diamond because they are new and have not been screwed up by 50 years of questionable maintenance.  Repairing airplanes which are nearing half a century old and have huge numbers of mods and crappy repairs is sadly something that can not be "Flat rated"

In my experience (28+ years) I have found that older Mooney's are among the worst maintained, followed closely by Piper Comanche's

Lastly compare your airplane shop rate at a factory service centre to a major name brand auto dealership and ask if you could make a living at the hourly rates most aircraft shops charge?

Clarence Beintema

Tri-City Aero,

Mooney, Diamond and Cirrus

 

[RJBrown]

There are flat rate manuals for the cars you describe. Both body and mechanical.

 I understand that not all jobs can be quoted by the book. Cars from rust belt areas that come here are much more time consuming to repair. That and other factors can cause a higher charge. We adjust the QUOTE to cover what we see. There are at times unforeseen factors that can increase a quote, but that is quite rare.

 The premise is that each repair has a value. My experience can adjust that amount to compensate for extra factors. ALL jobs are quoted ahead of time and any up charges are relayed to the customer BEFORE charges increase. We as pilots have been trained to accept vague answers and nebulous bills. If planes are really the complicated mystery that mechanics imply they are then maybe the mechanics don't know enough to do their jobs. A quote should be a contract not wild @$$ guess.

There are laws in Colorado that protect car owners from the " well that was just an estimate it really took this long to do it" type of operators out there. 

 The experience and efficiency level of the tech should not reflect in the cost of repair. A slow inefficient or experienced tech charges MORE for the same job? This is just wrong. To charge for "learning" by the tech is wrong. The "we did this this and that but could not change the complaint", but by the way here is the bill.  

I wish that airplane repair businesse could be held to the same pricing, estimating and billing standards that we hold.

[MOONEYAZ]

 had the same problem a number of times in my 201 about 25 years ago. Finally went out and bought jumper cables and kept them in the plane ever since and did need them a number of times.

I finally figured out the solution about 5 years ago. The power for the lights come from the dash board and feed both the front and rear overhead lights. I mounted a simple toggle on/off switch just over the pilots head along side the front light switch. With it in the up position, the light will work, and in the down position none of them can work. And I keep the switch in the down position unless I want the lights to able to light up. Haven't had a problem since.