Tag Archives: accident

Just Because the Helicopter Has Four Seats Doesn’t Mean You Have to Fill Them

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Or why I won’t do aerial photo/video flights with three passengers on board.

It’s that time of the season again: time to go through the NTSB reports to see how and why helicopters are crashing. As I’ve mentioned elsewhere in this blog, it’s usually due to “stupid pilot tricks.” Here’s yet another example.

The full narrative is a bit lengthy to quote here, but I’ll summarize:

R44 Raven I helicopter with four people on board. The pilot estimates the weight of the aircraft at the time of the accident was 2,391 pounds — just 9 pounds less than max gross weight for that aircraft. The accident occurred 25 to 30 minutes after takeoff. If the aircraft burns 15 gallons per hour (as conservatively estimated by Robinson), it burned at least 7 gallons during the flight. 7 gallons x 6 pounds per gallon = 42 pounds. So yes, the helicopter was over max gross weight at takeoff. No wonder the pilot “was concerned with the density altitude at the departure airport.”

Speaking of density altitude, the temperature was 31°C at the closest weather station, which was 12 miles away and sat at 4,964 feet. The calculated density altitude was 7,721 feet. The wind was 17G32.

The purpose of the flight was aerial photography. As any commercial pilot can tell you, that often means low and slow flights. So slow, perhaps, that the helicopter began to settle (under power) during a turn about 100 feet above the ground. There was a close call with two sets of power lines, which the pilot was able to clear while the low rotor horn blared. But the pilot was unable to gain enough speed and keep enough altitude to prevent settling into the ground. The helicopter rolled and three of the four occupants received minor injuries. The helicopter was totaled.

Out of Ground Effect Hover R44A look at the performance chart for an R44 (Raven I) makes it pretty clear why the pilot had trouble maintaining altitude at slow speed. At max gross weight on a 30°C day, the helicopter can’t even perform an out of ground effect (OGE) hover at sea level, let alone nearly 5,000 feet. That means it would have to continuously fly above ETL (approximately 25 knots airspeed) to stay in the air. At slow speed, a turn into a tailwind situation would rob the aircraft of airspeed, making it impossible (per the performance data, anyway) to stay airborne.

(It’s important to note that the R44 Raven II helicopter has much better performance at high density altitude. That’s why I paid the extra $40K to buy a Raven II instead of a Raven I.)

How could this accident have been prevented? Lighten up the aircraft. One way is to take just the passenger with the camera. Leaving two passengers behind would likely have lightened up the aircraft by 300 (or more) pounds. According to the OGE hover chart, at 2,050 pounds, the helicopter could (barely) hover out of ground effect. But even in that situation, the high density altitude would have made the helicopter sluggish and limited its performance. While an experienced pilot may have been able to pull it off, not every pilot could.

But this doesn’t excuse the pilot from doing his homework. A quick look in the pilot operating handbook (POH) would clearly show the aircraft’s limitations. The chart is in there for a reason.

Still, I could put myself in the pilot’s shoes and envision his situation. He knows density altitude could be an issue. But there are three guys and they see a helicopter with three empty seats. Why can’t they all fly? The pilot does a test flight with two of them on board and doesn’t have any trouble. What’s one more person, the passengers ask. Joey really wanted to come, too. The pilot succumbs to the pressure of this passengers and does something he knows deep down inside is probably very stupid.

And he pays for it.

How many times has this happened to you? Once?Twice? Ten times? I know that some version of this has happened to me. Every time it’s happened, I walked away without any problems. But during the whole flight, I worried. I knew what could happen. And I was relieved when things didn’t go wrong.

Is that the way we should be flying?

Hell, no!

Now I personally have a hard and steadfast rule: maximum of two passengers for aerial photo/video flights — preferably just one. And if I don’t feel like I have enough reserve power under the flying conditions — keeping the OGE Hover Chart in mind — I won’t do any hovering or very slow flight.

In my opinion, it’s not worth risking the safety of flight just to make a client happy.

Think about this the next time you’re preparing for an aerial photo mission.

The Sprained Foot

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Here’s how it happened and how it is three weeks later.

I didn’t blog about this when it happened. It may have been embarrassment. Or it may have been because my life got very busy for a while with house guests and day trips and life in general.

It was on Monday, August 5. I’d spent much of the day — the third or fourth day in a row — out at my future homesite in Malaga, clearing out invasive weeds along the driveway and the road in front of my house. It was hot, exhausting work, but I felt good at the end of each day. Like I was working toward a goal. (Am I the only person who feels that way while making progress on a project?)

That particular day, I’d been using a gas-powered hedge trimmer to cut weeds. I’d rented it from Home Depot. The tool did the job, but not as easily as I’d hoped. And it was a bitch to get started. I returned it that afternoon, contemplating the purchase of a chainsaw again.

On the way home — it was probably about 5 PM at the time — I stopped at the supermarket to buy groceries. Because I had so much junk in the truck I did something I very rarely do: I put the 5 or 6 grocery bags in the truck’s bed.

That was my mistake.

When I got home, I discovered that the grocery bags had shifted around in the back of the truck. So I lowered the tailgate and climbed up to gather them together. They were the usual plastic shopping bags and I grasped them by their handles with four in one hand and two in the other. I walked to the back of the truck, stood on the edge of the tailgate and crouched down with my butt about four inches off the tailgate. I put my right hand down on the tailgate and launched my feet off the back of the truck.

Keep in mind that this little jumping maneuver is something I do regularly. The distance to the ground is only about 3 feet. By crouching and launching like that, I minimize the impact of the landing. I do it all the time. I’ve never had a problem.

Except that Monday. As I launched my feet off, one of my feet — maybe my right? — got hung up on the rough surface of the spray-in bed liner. It could have been because I was tired from a full day at work, but it was more likely complacency — not thinking about what I was doing because I had done it so many times before. I didn’t make a clean jump. I realized this as I was falling and tried to recover.

I don’t know exactly how I landed, but I suspect my left foot took most of the impact on an angle. My left knee and the palms of both hands hit the gravel next. The grocery bags crashed all around me.

I immediately thought of the Tito’s vodka and Maker’s Mark bourbon what were in the bags. It would be a real shame to break the bottles of $50 worth of liquor.

But pain interrupted those thoughts. Lots of pain. I was hurting badly. I rolled over on my back and began taking inventory on body parts. One by one they checked in OK. Except my left foot. That was just registering pain.

I sat up and gathered the bags together. Neither bottle had broken. Whew!

I sat for a moment more. My left knee was bleeding but the palms of my hands were fine. That could have been worse, I thought to myself.

It was. When I tried to stand up, I realized I couldn’t put any weight on my left foot.

Oddly enough, I didn’t think much of the problem at first. After all, we’ve all gotten hurt in silly little accidents and after the initial shock wears off, everything works fine. I figured that my foot or ankle — whatever was sending those pain messages to my brain — was just whining a bit longer than usual.

In the meantime, it was hot and I was thirsty. I managed to get to my feet and sort of hop over to my RV. My porch was a bit of a challenge and I honestly don’t remember how I got up the stairs. I put down the bags of groceries and poured myself a glass of lemonade with lots of ice. I drank it all and refilled it.

My ankle was still sending those pain messages. What was up with that?

I sat down on the steps that lead up to my bedroom and pulled off my shoe. My foot seemed to explode into a swollen mass. I couldn’t move my toes.

This was not good. There was a chance, I realized, that I may have actually broken something.

I pulled out my phone and called my friend Kathryn, who lives in the orchard.

“What are you doing?” I asked once the greetings were over.

“Nothing much,” she replied. “Just hanging around, enjoying the weather.”

“Could you do me a favor?” I asked.

“Sure. What do you need?”

“Could you drive me to the hospital? I think I might have broken my ankle.”

The tone of the conversation changed immediately to once of concern and urgency. A few minutes later, Kathryn and her husband Donn were out in front of my trailer with their truck. I used a stepladder as a cane to meet them on the driveway and managed to climb aboard.

They took me to a local clinic, which they thought would be faster than a hospital. Donn fetched a wheelchair and wheeled me in. I did the paperwork at the desk. And then they waited 90 minutes with me. (I have such great friends.) Kathryn came into the examining room with me to keep me company. I was x-rayed, poked, and prodded. It was pretty obvious that the problem was in my foot — not my ankle. The verdict came from the nurse practitioner who’d been assigned to me.

“It’s not broken. It’s a sprain.”

“That’s good,” I said, relieved.

“No, it’s not,” she corrected me. “For people over 40, sprains are usually worse than breaks. They take longer to heal.”

She wrapped me up with an ace bandage, gave me a prescription for pain meds, and told me where to find crutches at 7:30 on a Monday evening. She also gave me a sheet with the standard RICE advice.

My friends took me to Fred Meyer. Kathryn went in and returned with a set of crutches. Then we went to Olive Garden for dinner (their choice). I had a terrible drink and an excellent meal, which I only ate half of. By the time I got home, it was after 9 PM. I was glad I’d remembered to put away the yogurt before leaving.

Sore Foot
The day after my mishap was spent in bed with my foot elevated. But it swelled up anyway.

In the morning, I was amazed by how bad my foot looked. I took a picture and put it on Facebook. I spent much of the day in bed, trying hard to keep my foot elevated above the level of my heart.

Do you know how hard it is for me to sit still when I have things to do? It was a miserable day.

The next day, I had things to do and I wasn’t going to let my swollen foot stop me. So I wrapped it up grabbed the crutches, and got on with my life.

Of course, during this time I was still on contract for cherry drying. I had some concern over whether I’d be physically able to fly. After all, flying a helicopter requires four limbs, preferably healthy ones. But I put those concerns to rest on Wednesday when I fired up my helicopter and flew it down to Wenatchee for some scheduled maintenance. Fortunately, my helicopter doesn’t require much pressure on the pedals.

I admit I didn’t follow the RICE advice to the letter. Although I slept — or tried to sleep — with my foot elevated on two pillows, I didn’t ice it as often as I was supposed to and I certainly didn’t rest it very much. I was on two crutches for just two days and then just one crutch for a week. After the first week or so, I realized that it looked almost normal when I got out of bed but swelled up to epic proportions within a hour of being up and around. The swelling included my foot and ankle — indeed, I had a chankle. I ditched the crutches entirely about 10 days after my mishap. That’s when I flew my helicopter to Seattle to pick up a friend and did the tourist thing around Pike Place Market and the Space Needle. It was pretty swollen that night.

I’ve turned down five invitations from friends to go hiking. You have no idea how frustrating that is.

But I’ve also been out on my boat three times. Not much walking involved there. Once, while fishing, I sat on the swimming platform and dangled my feet into the Wenatchee River. The nice, cool water was soothing.

I’m now starting week 4 of healing. I’ve found a good compromise. When I prepare to go out for the day, I wrap my foot firmly in the ace bandage, put a sock over it, and put on my good walking shoes — ironically, the same ones I was wearing when the mishap occurred. The shoe gives my foot the support it needs; it only hurts when I step on uneven surfaces. Because the flexing motion of walking also causes pain, I have a pronounced limp when I try to walk quickly. But around my home, it’s not that bad. Yesterday, when I unwrapped it, it didn’t even look very swollen.

If I behave myself and stay off the hiking trails, I’m pretty sure I’ll be 100% healed by the end of September. That’s a long time, but I just have to deal with it.

As for jumping off the back of my truck — well, I think this little incident has reminded me that I’m not 22 anymore. We’ll see if I remember this lesson in the months and years to come.

Unanticipated Yaw

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Some comments about one of Robinson Helicopter’s latest Safety Notices.

In May 2013, Robinson Helicopter issued Safety Notice SN-42, Unanticipated Yaw. It said, in part:

A pilot’s failure to apply proper pedal inputs in response to strong or gusty winds during hover or low-speed flight may result in an unanticipated yaw. Some pilots mistakenly attribute this yaw to loss of tail rotor effectiveness (LTE), implying that the tail rotor stalled or was unable to provide adequate thrust. Tail rotors on Robinson helicopters are designed to have more authority than many other helicopters and are unlikely to experience LTE.

I discuss LTE a bit in my 2009 blog post, “How Much Wind is Too Much Wind?” You can also learn about it on Wikipedia and in the FAA-published Helicopter Flying Handbook.

Bell 206 Tail Rotor
Bell 206 helicopters have dinky tail rotor blades. (Photo Credit: Dakota Air Parts.)

Robinson points out that its helicopters are designed to have more authority than many other helicopters. This is partly because Frank Robinson worked for Bell, which has notoriously poor tail rotor authority, where he became known as a “tail rotor expert.”

I experienced the difference between tail rotor authority in a Robinson vs. another helicopter firsthand in 2004, when I flew Bell 206 Long Rangers at the Grand Canyon. After years and at least 1200 hours experience flying Robinsons, I was in a quartering tailwind at the Papillon helipads one day and got into LTE. I pressed the pedal enough to stop the rotation in a Robinson, but the yaw didn’t stop — I wasn’t flying a Robinson. Fortunately, I had the presence of mind to press harder on the pedal and get the situation under control before the rotation had reached a full 90°. It taught me a very valuable lesson about unanticipated yaw.

Robinson’s Safety Notices are normally issued in response to specific accidents. I went fishing on the NTSB website and discovered this April 2012 accident. Probable cause was issued on May 23, 2013 and that would be the right timing for a Safety Notice to appear. (Of course, I can’t be certain whether this is the accident that sparked the new Safety Notice. It’s just a guess on my part.)

From the report summary:

The helicopter slowed as it approached the landing zone on a modified right-base turn to the north. Gusting wind from the south had prevailed for most of the day and was present at the time of the accident. As the pilot turned to “enter the landing area,” he felt a “bump” in the tail rotor control pedals. The pilot added that he applied left pedal to compensate for a right yaw, and the helicopter immediately “started to rotate” at an increasing yaw rate with full left pedal applied. The pilot stated that the rotation stopped when he pushed the collective control “full down” and applied aft cyclic. The helicopter then descended through the trees and collided with terrain. Examination of the wreckage revealed no evidence of pre-impact mechanical anomaly.

The accident report goes on to provide general information about LTE. The Full Narrative refers to FAA Advisory Circular (AC) 90-95 “Unanticipated Right Yaw in Helicopters.” It also refers to Robinson Safety Notice SN-34, Photo Flights – Very High Risk as it pertains to settling with power, reduced RPM, and the loss of tail rotor thrust in low RPM situations. All of this is good reading to learn more about LTE and tail rotor operation.

It’s in low-speed situations that tail rotor effectiveness can be lost. At higher speeds, the helicopter points into the wind via normal “weathervaning.” The vertical stabilizer on the end of the tail helps make this happen. But at lower speeds, especially when turning into a tailwind, the force of the wind can easily cause the helicopter to yaw. The pilot must react quickly and firmly to stop and correct the yaw.

Experience teaches us. Years ago, I was doing a long cross-country flight with a 300-hour pilot who had just gotten his CFI. He was landing at San Luis Obispo (SBP), sitting in the left seat while I sat in the right. There was some yaw and I think he tried to correct it with the pedals. But then he panicked and said that something was wrong, that the pedals weren’t working.

I don’t recall the yaw being very bad. We were still moving along at a good clip, barely over the runway and likely doing at least 50-60 knots. I told him to push the pedal and he claimed he was and that it wasn’t working. He was visibly upset. I offered to take the controls and he agreed. I pushed the appropriate pedal and the helicopter immediately straightened. I landed without incident.

When I read this Safety Notice, I immediately thought of that low time pilot’s approach to landing and my own experience, years before, at the Grand Canyon. In both cases, we’d initially failed to use enough pedal to correct the yaw. The difference is, while I’d added more pedal when necessary, the low-time pilot had assumed there was a problem with the aircraft without trying harder to correct the yaw.

I have to wonder whether the accident pilot was in the same situation. After all, probable cause put the blame firmly on him:

The pilot’s inadequate compensation for wind during a high-power, low-speed downwind turn, which resulted in a loss of control due to loss of tail rotor effectiveness and settling with power. Contributing to the accident was the pilot’s decision to land downwind.

I guess the takeaway from all this can be summed up as follows: We always need to be aware of potential control issues, especially when operating at low speeds in crosswind or downwind situations. Yaw should never be “unanticipated.” It’s the pilot’s responsibility to keep control of the aircraft at all times by avoiding situations that could result in control issues and to use aircraft controls properly.