TangoWhiskey
Touchdown! Greaser!
Lucky? Yes, lucky that I didn't have an engine compartment fire in flight, with my wife on board. And while I tend to think of myself as a "cautious and careful" pilot, I missed (and dismissed) two clues that could have stopped the chain. That's why I'm writing this story.
Returning to Fort Worth (T67 / Hicks) from a two week trip to New Smyrna Beach ( KEVB ), my wife and I planned a stop in Meridian, MS (KMEI), for a lunch snack and fuel. Meridian is well known in the area for affordable gas, free hot dogs, pizza and popcorn. We filed IFR, and after a quick hop up on top of a 500' OVC, but thin, fog layer in New Smyrna Beach, we were on our way in our 1980 TR182. While we'd flown high eastbound to Florida, on the return trip we stayed low, at 8000', due to the strong westerlies. This ended up being, I think, a "good thing."
After our one hour stop in Meridian, we saddle up and got ready to go. We use a Mountain High O2D2 pulse-delivery system connected to our shipboard oxygen system, and wear it on most long flights at 8000' or above--we seem to arrive fresher and with no headache that way. Pre-engine start, we donned our cannulas, put on our headsets, opened the O2 valve and set the O2D2 unit for D5, as usual. After engine start and avionics on, I remarked to my wife that the engine seemed a little "louder" than normal. She agreed. It almost sounded like we didn't have ANR activated on our Lightspeed Zulu 2's, so we checked that, but indeed it was on. Turning ANR off made it get louder, ANR on was not as loud, but definitely louder than "normal". Not a grinding or metallic sound--just sounded like we had another 300HP! Maybe I was dreaming of flying a twin? In any case, after a check of the engine instruments and such (all normal), we decided to go do a thorough runup before departing on our final leg home.
We picked up our IFR clearance and taxied from the FBO's ramp via taxiway Bravo to the run-up area for Runway 4. We did an especially careful and thorough (and longer than normal) runup, double checking our headsets. The engine still seemed loud, but we noticed that when we pushed the earseals in (like pushing on your head when you have a migraine), the sound did get "normal". So, we both wrote it off as a bad ear seal due to the O2 hoses, or some other ANR issue.
On the roll for departure, it took a lot of willpower (and in retrospect, stupidity) to ignore the louder-than-normal sounding engine, but everything was in the green, no issues at all. We climbed direct to 8000 and proceeded 2 hr. 45 minutes home to Fort Worth.
About 30 minutes into our 2 hr 45 minute flight, during a routine scan my eyes alighted on the yellow, green and blue Quantum Eye CO detector I have mounted on the panel (as so many of us do). The dot was dark. Hmmmmmm. That's got my attention!
I have a ultra-sensitive CO Experts Carbon Monoxide detector unit on board, and I pulled it out and fired it up. The levels looked "fine" (25 ppm and under, depending on where we held it in the cockpit), and weren't increasing. (see link below for info on "normal" levels--I will likely adjust my threshold on what defines "fine").
"So why was is dot on the card black?", we wondered. "Oh, yeah, we spent a long time in the runup area with the windows open!", we excused.
"Let's check our O2 levels", I suggested. "Since CO binds to hemoglobin, our SpO2 readings should be lower than normal if we really have a CO problem, the SpO2 measured oxygen saturation levels should be lower than what we've seen historically." We both check, we're both about 95%. "OK! We're good!" We soldiered on. Rest of the flight was, LUCKILY, uneventful.
What was really going on, for which I had at least two clues that I "wrote off" as something innocuous, when in reality my plane was trying to tell me "something's not right, buddy!"?
I was hearing an exhaust leak! A post-flight check of the engine compartment by my mechanic revealed a broken exhaust clamp:
Now, interestingly, I had opened up the engine compartment and done my own detailed post-flight inspection and DIDN'T SEE THIS. I'm not sure if I'd have caught it even if I'd listened to the "clues" at Meridian and gone back and pulled the cowl. In the future, of course, I will... knowing what "that" sounds like.
So, a number of errors / lessons learned:
MOST IMPORTANTLY: An SpO2 meter will NOT clue you in on CO poisoning! See the links below. It's this fact alone that sparked me to write the story--pilots need to know this. The molecules for CO "look the same" as O2 molecules to our aviation fingertip SpO2 meters! I quote: "A pulse oximeter cannot distinguish the differences and the reading will show the total saturation level of oxygen and carbon monoxide. If 15% of hemoglobin has carbon monoxide and 80% has oxygen, the reading would be 95%."
So, please please please read up on Carbon Monoxide poisoning:
Secondly, I had multiple clues, and was willing to write them off to other causes. Yes, I did "diagnose" the problem and had a "reasonable explanation" for why something seemed amiss. But I was WRONG.
Stop. Check it out. On the ground.
I was lucky. I hope I'll be smart in the future, so I don't have to be lucky again.
Returning to Fort Worth (T67 / Hicks) from a two week trip to New Smyrna Beach ( KEVB ), my wife and I planned a stop in Meridian, MS (KMEI), for a lunch snack and fuel. Meridian is well known in the area for affordable gas, free hot dogs, pizza and popcorn. We filed IFR, and after a quick hop up on top of a 500' OVC, but thin, fog layer in New Smyrna Beach, we were on our way in our 1980 TR182. While we'd flown high eastbound to Florida, on the return trip we stayed low, at 8000', due to the strong westerlies. This ended up being, I think, a "good thing."
After our one hour stop in Meridian, we saddle up and got ready to go. We use a Mountain High O2D2 pulse-delivery system connected to our shipboard oxygen system, and wear it on most long flights at 8000' or above--we seem to arrive fresher and with no headache that way. Pre-engine start, we donned our cannulas, put on our headsets, opened the O2 valve and set the O2D2 unit for D5, as usual. After engine start and avionics on, I remarked to my wife that the engine seemed a little "louder" than normal. She agreed. It almost sounded like we didn't have ANR activated on our Lightspeed Zulu 2's, so we checked that, but indeed it was on. Turning ANR off made it get louder, ANR on was not as loud, but definitely louder than "normal". Not a grinding or metallic sound--just sounded like we had another 300HP! Maybe I was dreaming of flying a twin? In any case, after a check of the engine instruments and such (all normal), we decided to go do a thorough runup before departing on our final leg home.
We picked up our IFR clearance and taxied from the FBO's ramp via taxiway Bravo to the run-up area for Runway 4. We did an especially careful and thorough (and longer than normal) runup, double checking our headsets. The engine still seemed loud, but we noticed that when we pushed the earseals in (like pushing on your head when you have a migraine), the sound did get "normal". So, we both wrote it off as a bad ear seal due to the O2 hoses, or some other ANR issue.
On the roll for departure, it took a lot of willpower (and in retrospect, stupidity) to ignore the louder-than-normal sounding engine, but everything was in the green, no issues at all. We climbed direct to 8000 and proceeded 2 hr. 45 minutes home to Fort Worth.
About 30 minutes into our 2 hr 45 minute flight, during a routine scan my eyes alighted on the yellow, green and blue Quantum Eye CO detector I have mounted on the panel (as so many of us do). The dot was dark. Hmmmmmm. That's got my attention!
I have a ultra-sensitive CO Experts Carbon Monoxide detector unit on board, and I pulled it out and fired it up. The levels looked "fine" (25 ppm and under, depending on where we held it in the cockpit), and weren't increasing. (see link below for info on "normal" levels--I will likely adjust my threshold on what defines "fine").
"So why was is dot on the card black?", we wondered. "Oh, yeah, we spent a long time in the runup area with the windows open!", we excused.
"Let's check our O2 levels", I suggested. "Since CO binds to hemoglobin, our SpO2 readings should be lower than normal if we really have a CO problem, the SpO2 measured oxygen saturation levels should be lower than what we've seen historically." We both check, we're both about 95%. "OK! We're good!" We soldiered on. Rest of the flight was, LUCKILY, uneventful.
What was really going on, for which I had at least two clues that I "wrote off" as something innocuous, when in reality my plane was trying to tell me "something's not right, buddy!"?
I was hearing an exhaust leak! A post-flight check of the engine compartment by my mechanic revealed a broken exhaust clamp:
Now, interestingly, I had opened up the engine compartment and done my own detailed post-flight inspection and DIDN'T SEE THIS. I'm not sure if I'd have caught it even if I'd listened to the "clues" at Meridian and gone back and pulled the cowl. In the future, of course, I will... knowing what "that" sounds like.
So, a number of errors / lessons learned:
MOST IMPORTANTLY: An SpO2 meter will NOT clue you in on CO poisoning! See the links below. It's this fact alone that sparked me to write the story--pilots need to know this. The molecules for CO "look the same" as O2 molecules to our aviation fingertip SpO2 meters! I quote: "A pulse oximeter cannot distinguish the differences and the reading will show the total saturation level of oxygen and carbon monoxide. If 15% of hemoglobin has carbon monoxide and 80% has oxygen, the reading would be 95%."
So, please please please read up on Carbon Monoxide poisoning:
- http://www.cpsc.gov/en/Safety-Educa...enter/Carbon-Monoxide-Questions-and-Answers-/
- https://www.kane.co.uk/knowledge-centre/what-are-safe-levels-of-co-and-co2-in-rooms
- https://www.amperordirect.com/pc/help-pulse-oximeter/z-pulse-oximeter-limitations.html
- https://www.instrumart.com/assets/COintheCockpit.pdf
Secondly, I had multiple clues, and was willing to write them off to other causes. Yes, I did "diagnose" the problem and had a "reasonable explanation" for why something seemed amiss. But I was WRONG.
Stop. Check it out. On the ground.
I was lucky. I hope I'll be smart in the future, so I don't have to be lucky again.
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