PA25-235 Sinaloa MX Gender Reveal Party Structural Failure 

Gender reveal parties have long been over the top. Now it just seems like it's out of control.

Retired ag pilot here. I started out in a Pawnee 260 C model. It would carry the 150 gallons, I doubt that the 235 version could. That being said, I didn’t notice you saying anything about the hopper being well forward of the CG. I’ve dumped many times. There’s always a violent pitch up if you’re not trimmed in advance for it. If he also pulled back at the same time, then that would certainly overstress the aircraft. As previously mentioned, corrosion was probably involved.

I had to rewatch the part about why maneuvering speed decreases with weight... I don't know if I'm the only one who got a little lost, but I could still use a deeper dive into the physics. I appreciated that you explained it multiple ways, but for some reason it's still not clicking for me. Thank you for diving into these tragic events so that we can all learn to be better and safer pilots.

Juan, let me add some details from my experience working as a aircraft structures certification engineer: It is true that the maneuvering speed vA is defined by vS times the square rout of the design load factor. However, it is not a limit up to which the pilot cannot damage the airplane. vS is a calculated stalling speed (FAR/CS 23.335(c)), as estimated early in the design process. vA is a defined airspeed limitation to be used mainly for control surface and control system structural sizing. FAA AC 23-19A explains: "VA should not be interpreted as a speed that would permit the pilot unrestricted flight-control movement without exceeding airplane structural limits, nor should it be interpreted as a gust penetration speed." The TCDS you present in this video is of a restricted category aircraft. Although limit maneuvering load factors seem not to be mentioned in this TCDS, in the restricted category certain limitations can be lowered below the FAR-/CS-23 minimum requirements, including limit load factors and structural safety margins. That is especially used for cropdusters to allow higher take off masses. As far as wing structural loading is concerned: it does actually not change when you empty the hopper tank. Given, that speed and angle of attack stay the same. Why is that? The aerodynamic forces on the wing are unchanged as long as airspeed, angle of attack and it's configuration (flaps, ailerons) don't change. So the lift force doesn't change. The same lift force acting on a lighter fuselage lighter than before means the vertical acceleration increased, as Newton claims in his second law. To maintain level flight, i.e. maintain 1g, the pilot needs to reduce the angle of attack during release of the payload, as you explain. It seems that the unlucky pilot in the video did the opposite and increased the angle of attack, leading to increased lift forces, which resulted in structural failure of the wing.

I remember as a kid watching in Bishop Ca, a contract pilot showing off in a Turbine Aero Commander make a high speed run down the runway then pulling up hard. The mechanic the next day noticed fuel leaking out of the left wing. Measuring the wing tips, the left wing was 9 inches higher off the ground and the top of the wing was wrinkled. He was no longer a contract pilot.

I miss the good old days when the cigar ring had the blue or pink on it. A simpler time.

I don’t know why this was recommended by the algorithm but you did a great job explaining and teaching. Thank you.

I’m a chemistry guy with no aviation knowledge, but this was so easy to follow while still diving into the technical. Excellent

I began my ag flying career flying the Pawnee and I never flew with more than 100 gallons. Never filled the hopper with liquid but we used the large hopper for dry fertilizer. I was trained at Ayers Corp. in Albany Georgia, where they make the thrush aircraft. You had to do a demonstration flight to get certified FAR 137 and part of the flight was a emergency dump. You had to learn to push the stick forward hard to keep the aircraft level cause dumping that much weight the aircraft wanted to climb like all get out.

I used to fly PBY water bombers and we called it “checking forward” as we dropped the load. With practice, you could time it just right, so you wouldn’t even feel the load being dropped.

Amazing how everyone saw the wings fold and the plane start spinning but didnt miss a beat with their task on the reveal or miss the shot.

Wow, what an educational video. That explains why there are several videos floating around the web showing structural failure AFTER dumping the load. Never made sense to me, but now I understand. I am a commercial pilot, helicopter, multi-engine, instrument rated, as well as A&P mechanic (all in the past, I am 80 years old). I was always keenly interested in areodynamics, and so am really grateful for your explanation of maneuvering speed dependence upon wing loading. As an A&P, I have performed the wing spar attach AD you talk about. I always liked the Pawnee 235, a very smooth and capable airplane, and a shame to see one lost. Thanks again.

Juan with a PHD level lecture. No distractions no opinions no judgments, stayed on topic with serious attitude, as it deserves. Operating an aircraft or any other vehicle that may hurt or kill someone deserves to be taken with the most high responsibility.

Coming from a third generation ag pilot, great break down of this accident a lot of people misunderstand accidents in the ag world. Although mistakes were made, I am also leaning to the fact there was probably corrosion involved. Great job Juan keep up the good work.

This is again a sad story where pilots are pushed towards being a “flying circus” with a bad outcome. I will file this video for all my aerobatic, UPRT or instructor students, when I’m desperately try to explain a flight envelope. Thank you Juan for doing it for me! I like the visualisation with different colours. 👍🏻

While it is true that low weight does increase max Gs for the same control input at any given speed, the lift of the wings and so the couple at the wings roots is the same, so I don't see how low weight can be to blame for this kind of structural failure. Other parts of the airframe indeed are more stressed with more Gs, but not the wings because of this low weight situation. Thanks for your response, it meens a lot for us GA pilots your videos. Congrats.

0:17 I love how whoever is operating the camera paid enough attention to the plane to stay with it as the wings fold, but then just pans back to the soon-to-be parents as if they didn't just see what we all saw. "Screw that guy... it's a girl!" 🤔🤨

Many years ago ('94-'95), as a young A&P, we had a Pawnee with Hutch metal wings that were just full of cracks. We pulled the wings to repair them and found the fuselage wing attach points badly rusted internally. They looked great with nice paint on the outside, but just ugly inside with much material missing. It left on a truck to an aerospace welding facility for replacement. Scary stuff considering how they get yanked and banked in a highly corrosive environment.

Flying fighters, we use a version of the V/G diagram to show 2 important features of performance-corner velocity (smallest turn radius which happens to match Vm) and best turn rate airspeed (faster and G-limited). If you lay two competing [Em] diagrams on top of each other, you can find your maneuvering advantage. As always, fantastic video Juan.

Maneuvering speed was an area one of my instructors drilled into me. (I had three total and lost each one as they moved up into the airlines) I’ve never seen that chart before but I can say that its a great tool, especially if you want to explain why less weight will decrease maneuvering speed. I assume the same logic would apply when 12 skydivers exit an aircraft. Great teaching moment. I enjoyed the entire presentation.

As someone who owns and flies a PA-25-235 Pawnee for aerial application, I’d like to clarify a few things: 1) A Pawnee 235 usually reaches its gross weight with around 100-110 gallons of water (8.3 pounds per gallon) and proportionately less with many ag chemicals that can weigh 9 to over 11 gallons per gallon. Most ag pilots who fly or flew Pawnees don’t advise flying with any more than 90-100 gallons. Mine has an updated 260 Hp engine, and while it has ample power to come out of a field and maintain speed in a turn, it’s still short of wing area. With more than 100 gallons (or 830 pounds) in the hopper, the stall speed starts to get uncomfortably close to the accelerated stall speed in a 45 degree turn. My Pawnee with myself and 41 gallons of fuel reaches its gross weight with 107 gallons of water. That last 50 gallons of hopper capacity is only useful for seeding and other operations with lower density dry materials. In short, the weight change was at most on the order of 800 pounds rather than 1200 pounds. 2) A Pawnee with a load and spray equipment will do a maximum of about 105-110 mph at 75% power and even at full power would be unlikely to exceed its Va of 120 mph. My Pawnee 235 has an updated engine producing 260 hp but with its fixed pitched propeller my Pawnees still won’t exceed Va with a full load and spray equipment. Based on both its plying traits and what I see in the video, I don’t see any indication of excessive airspeed in this video. 3) Most ag planes do pitch up during an emergency dump. Ag pilots, like fire pilots flying ag aircraft as single engine air tankers, use forward stick to offset this pitch up tendency and can do it with no pitch up being evident. Students attending ag schools do emergency dumps as part of their part 137 training and very few anticipate the pitch up quickly enough and/or with enough forward stick in Pawnees and in aircraft that pitch up more than a Pawnee but the wings don’t fall off. 4) The Pawnee’s pitch up tendency is comparatively mild, even when dumping a full load. When dumping a full 100-110 gallon load an uncorrected pitch up is still only on the order of 1.5-2.0 G. 5) More to the point, if you don’t mitigate the pitch up with forward stick it looks just like the Pawnee in the video prior to the pitch up. The initial pitch up before the wing separation isn’t out of the ordinary. Even if the pilot added back pressure to make it more spectacular, it’s not a pull anywhere near the damage and failure limits on the VG diagram, even 800 pounds below gross weight. You did discuss the 1995 AD that required periodic and extensive (wing removal and dye penetrant testing) every 24 months, or new wing attach fittings and repetitive replacement every 60 months. Later there were three STCs for new wing attach fittings, two of which retired the AD. Most Pawnees still out there have been modified with the new STC’d attach fittings at some point since 1995 when they have been rebuilt and recovered. The problem is unless you know what you are looking for and look to ensure the new STC’d attach fittings were actually installed, you have no idea if the AD was complied with or just pencil whipped. Similarly there is no way to know whether a 24 month or 60 month inspection was actually done if the aircraft has the original fittings. It’s not a common issue in the US, but Bic maintenance is a bigger potential issue south of the border, where these wing separations happen.

These crop dusters are loaded to cover several fields before they need to be reloaded. The emergency dump is used if you have a in flight emergency and have to take weight off of the air frame for an emergency landing.

I've got around 7000 hours in the PA-25 235 as an aerial advertising pilot (banner towing). Our operating manual had the maneuvering speed listed (yes it is 120 MPH). I'm glad you started by mentioning the variable maneuvering speed as the weight changes. Our planes were STC'd with 75 gallon tanks where the hopper used to be (3 gallons unusable) so we had to be aware of the maneuvering speed vs weight difference as we flew cross-countries to different locations. It's a very fun and rugged airplane when used correctly. I usually called it the flying pickup truck.

Great video Juan! If I understand correctly, because the mass of the load being dumped is about 80% of the empty weight of the plane, after release, the instanenous g-load is increased to 180% of the value before dumping. Thus if the plane is already pulling 2 Gs at the moment of dumping, it is now pulling 3.6 Gs the moment after dumping. No wonder things snap.

Dumping the hopper causes an extreme nose up trim, it will take you by surprise if your not ready for it. A massive push on the stick is required during the dump. I am guessing he was a banner or glider tow pilot, not an ag pilot.

As a private pilot this was never mentioned to me and I was unaware that at minimal weight this could be a factor. I guess that's why they call it a license to learn. Great video.

I used to fly the Pawnee (later the Canso) spraying in Africa, in the 70s. It is now a nostalgic chapter of my life and I found this video both illuminating and sad. Thanks Juan, you ALWAYS produce such high value information. Pilots would do well to follow EVERY ONE of your videos. Thank you.

Aero Engineer here with a lot of ag design/testing/certification testing..... When you emergency drop, the effluent drops down entraining air which increases the angle of attack at the horizontal tail which increases the down force at the horizontal tail. This tends to pitch the aircraft nose up without any input from the pilot. A number of AT-802's have been lost because of this phenomenon, but in this case the horizontal tail stalls and the aircraft bunts (uncontrollable nose down).

This is a great analysis. Really sorry for the pilot and family. RIP. Corrosion will be a factor, no doubt. It's always somewhere isn't it.

Your chart explains why I’m not an Engineer. All I knew was the weight changed and he stressed the plane’s limits. Thank you for the explanations.

That “ahah” before the Argentinian reveal was peak dad joke reveal. Love you Juan. Keep the content coming!

Thanks! There are numerous Airworthiness Directives on the struts, the one you showed for the main spar attachment and another for the aft spar attach. It does not look like either of those failed. As you mentioned, it does appear that the left wing failed at the outboard strut attach point. I’ve not done crop dusting with these birds, but I do have over 600hrs in Pawnees on glider tow duty. We are about 1200# below MaxGW. You are hard pressed to get over 120mph in a dive without that extra weight.

And they didn't even see the aircraft breaking and crashing and just continue celebrating! 😡

I had seen personally three of that aircraft in the early 70's where the tubing next to the tail wheel was corroding apart from the chemicals, speaking of such, why would anyone, especially pregnant, want pesticides and defoliant tank water to be dropped on them???

I have always loved aircraft but I am not a pilot. This is an excellent reminder to me why I should never try to fly. The details that must be remembered around the weight, G-force, stall speed, etc... are not my strong suit. Would love to be a mechanic again, but you guys that are (good) pilots get all my respect.

Juan, I love how can you be such an aviation nerd AND help us fellow aviators with your experience, research and insight at an understandable level. Keep 'em coming, and come visit us in Idaho again sometime!

Thank you for explaining this. The old C130 that lost both wings is an example as well.

Excellent video as usual! As a sometimes-getting-paid-for-it aerodynamics by training Ph.D. I view this through the basic physics lens. The force on the wings is proportional to the AoA and square of the airspeed (hence the exponentially rising limit curve vs. air speed). For a given speed, at heavy weight when you pull back on the stick the airplane cannot increase it's angle of attack quickly due to the airframe/load inertia and thus the rise in force on the wings is slow. At low weight when you pull back on the stick the AoA can rapidly increase because of the lower inertia/weight and quickly get to the point of generating a huge amount of force that's trying to yank the rest of the plane upward. Ever put your hand out the car window like an airplane wing and tilt it upward a little too much too quickly and your hand snaps upwards. If your hand was made of lead it would snap upward far more slowly than your water-ish made hand. That and the heavy plane/hand was already at a higher angle of attack to counter the aircraft weight/hand weight to keep it in the air. Ever see a light paper/balsa wood airplane suddenly get too much lift it pitches up very quickly whereas a heavier paper airplane does not pitch up nearly as fast. Excellent video as usual.

Juan, as always a spot on analysis of a tragic event. I have great respect for your aviation knowledge! I'm not sure if you know, but when a RU-vid video is paused you can use the greater than less than keys to move one frame at a time. I find it useful on many videos when trying to see something important. Of course the quality of the freeze frame depend on the quality of the video. Cheers!

I didn’t recall the issue of how changing the A/C load effects maneuvering speed. Thanks Captain.

It looks like the left wing bent backwards, causing a runaway pitch-up moment until it snapped off. That is, in the first frame where the wing flexes it looks like the wingtip flexes first, rather than at the root. You can even see the wing crease just outboard of the root.

Grandma killed by shrapnel, massive wildfire and now a dead pilot. How about just saying "it's a boy".

Juan, extremely well done. Thank you for the effort into the clarity and detail.

Thanks a lot Glenn. An extremely clear lesson on structural limits. And the difference between an oooold crop dusting utility aircraft (turned into a light firefighter aircraft) and an aerobatic aircraft…

Great class for all pilots. Usually, there is more than one link broken for an accident to happen, this may well be the case. Thanks Juan. Poor guy didn’t know what he was getting into. RIP.

Once again you did an outstanding job gathering all this info and putting it all together so we can all understand and learn from these horrible accidents.

This is a remarkable presentation from Juan Browne and I will surely pass the message to our club members here in Alsace (France). Thanks 👍

Dear Juan as an engineer i am not sure I agree with your explanation. Dropping weight before/during the pull up actually reduces the load to be carried by the airframe. So the drop is not the problem in my opinion but the sharp pull up that exceeded the limits of the wing. The CL215s always do sharp pull ups during the drop while fighting fires. Just my two cents and greetings from Athens.

Great video Juan, as always. One detail: if you step through the video you’ll see the spar attach did not fail but the struts collapsed. First the rear (the wing twists in torsion first) then the front strut, and whole wing rotates around the fuselage about the spar attach pin.

It's amazing to me the lengths ppl will go to reveal a gender of a baby. Pilot killed, wild fire started and so on so on. Call or text your friends it a boy or girl. Ppl died because of this nonsense, enough all ready

Thanks for another informative analysis. I'll have to run through this a couple of times to fully understand it. I don't remember this being taught as a PPL topic but that was long ago.

Great analysis and explanation of this mishap Juan! Thanks for bringing us this great content.

Really great breakdown, as soon as I saw the crash video a few days ago, I thought "I hope Juan makes a breakdown video on this crash".

What a tragic event, that was supposed to be full of joy. My deepest sympathies go out to the family and friends of the pilot.

Thank you for the work you do examining these incidents.

Great reminder to all of us sir!! Some aircraft are more susceptible than others. I loved the way you went back to the basic chart to reiterate how dangerous exceeding design limits can be!!! Thanks again Juan!!!👍

Dying fighting fires or some other practical function is bad enough, but dying for something so utterly ridiculous and pointless is even worse.

I wonder how the child will feel about this when she grows up.

Good technical review Juan. It’s sad to learn from these accidents but learning all that we can take with us as pilots.

As you said it, Va is about protecting the fixed weight components, NOT the airfoils. So, at gross weight, the wings can withstand 16,530lbs before breaking .(2,900 lbs x 3.8g x 1.5). If it suddenly loses 1,000lbs of weight, the wings should then be able to withstand 8.7gs before breaking. (16,530lbs/1,900lbs). Going near 8.7gs would, of course, damage other components in the aircraft. Engine mounts, avionics trays, battery trays, etc. There is no way that the pilot exceeded the certified load limit of that aircraft. This was entirely a maintenance induced failure.

Unfortunately, I could not wait for today's class. Once again you did a stellar job. Sir, you save lives with your channel. Sorry for the pilot and his family. RIP young man.

In the first clip it seems the party attendees didn't notice the crash...? Sad indeed and well done Juan.

Hey Blanco, when the water is dropped rapidly, remember the wings were making 3,000 lbs of lift but the aircraft now weighs only 1,600 lbs. The airplane climbs violently, sometimes exceeding the available down elevator.

Thanks! This is a valuable lesson....one that I've never heard before. My initial intuition was wrong regarding Va.

Suggestion - attach smoke canisters, approach with white smoke, switch to pink overhead, fly tomorrow.

That was the best explanation of the danger of exceeding normal or lower Vp I've read or heard. Thanks Juan!

I love watching videos of someone telling me what I can read for myself

A a fantastic overview there Juan. Thank you.

Our gender reveal was 20-30 homemade cards mailed to friends and family. I’m sure they spent more time looking at the cards than these party guests spent pondering an associated death. I’m sure some of this is due to people’s wide-ranging ignorance these days. Some of the Wings over Dallas phone footage captured people asking whether all the aluminum falling from the sky was part of the show. As for this crash, it’s pretty close to call, but it looks to me like the wing was already tweaked before the rapid nose-up.

As I recall… during the low level skip-bombing assault on the Ruhr Valley Dams during WWII, 5 of the 8 attempts resulted in loss of aircraft to both defensive gunnery and catastrophic structural failures.

Outstanding, as always! Every video is packed full of critical knowledge. Thanks

Great explanation. I remember when I was instructing, at a couple flight training seminars/meetings (I think one was when I was renewing my instructor rating), a flight test examiner mentioned that flight test questions (usually posed to CPL candidates) about maneuvering speed were consistently some of the poorest answered across the country (mind you this is Canada and not the US). There does seem to be a lack of understanding, even among some licenced pilots, about what Va is, how and why it changes, and so on.

wow I never thought about it, counter intuitive and scary.. of course I never had the option to dump all my passengers out the bottom of the aircraft and yes I have had my mother-in-law in the back before :)

Thank you for covering this tragic loss. You have given me a good understanding of what went wrong

As a pilot and someone who works on aircraft, Pipers aren’t structurally built as well as a Cessna. If you go through the boneyards you’ll find pipers fill these yards. Rarely will you find a Cessna with a broken wing spar. I’d bet had he been in a different aircraft the spar would have bent, but not broken. Great job explaining what could have gone wrong. Condolences to his friends and family.

Thanks for the clear explanation, Juan. So glad no one on the ground was hurt. So sorry for the family of the pilot.

A life is worth so much more than the fleeting momentary thrill of seeing colored water drop from a plane for a gender reveal. I'm so sorry for the pilot and his loved ones.

Wouldn't have even thought that dropping something (heavy) from an aircraft would be legal, outside of some exceptions like agricultural or fire fighting activities. Far better to release colored smoke or something like colored confetti/chaff

You can calculate Va for any given weight . Va = (Va @ max weight) X square root of (current weight / Max gross weight)

Superb analytics so clearly explained Thanks so much Chris Cambridge UK

I'm just wondering how much Ag spraying experience the pilot had... thinking not much.

I was trying to explain to maneuvering speed to a student pilot the other day. This was a grim demonstration of its importance and the results of exceeding it.

Juan, you did a great job treating this seriously… Very professional, no stupid joking around. “Just the facts,Ma’am.” -Sgt. Friday

I always seem to learn more about flying whenever I watch one of your videos. However this one was an exceptionally informative and wrenching lesson on what NOT to do, to stay alive. Thanks for this.

Indeed... Many unfortunate things revealed during such a tragic event. Thanks Juan.

This has happened before, a few years ago, at a wedding I think. A family member flying. Tragic. Can't remember where.

As usual Juan very nice presentation . I'm also inclined to believe that over time , especially due to the type of operations this aircraft was used in ,it had been overstressed on numerous occasions . The general aviation fleet is aging and this certainly should be taken into consideration when flying them .

As always, an excellent and informative presentation. Thank you, sir!

Thx for a complicated but clear explanation of this strange, unfortunate event.

Early Pawnee ‘s had wooden wings which have broken. Most were updated to aluminum. We used them for banner towing as some companies still due. That could have happened here.

I am sorry for the Pilot and his family but definitely important for others to learn from this!

This is why I'm your patreon! You are able to explain short and clearly, whatever may be intrincate and hard to pick up from harsh or sad events like this!

I used to Tow banners and gliders in a 260 hp Pawnee. Very rugged plane. Very easy and forgiving to fly. I’m guessing the pilot must have pulled very hard here to cause structural failure even accounting for the sudden weight change.

No telling how many G's had been pulled on that aircraft during its life of dusting, particularly if the same Pilot had been flying it.

Every day is a school day, thanks for sharing your insights and the diagram. Condolences to those impacted by this unfortunate event.

If I had nickel for every gender reveal disaster…

Thanks for the insight Juan. It only takes one mistake to pay with your life. Simply put "small corrections" That's what my Dad would say when I was first learning to fly as a kid. I was a career pinch hitter with my Pops you could say. Every flight was a learning experience :)

Thanks, Juan! I really learned something from this video. I'm going to listen again.

So sad to see. You are absolutely right Juan it is counterintuitive. I’m sure I’ll have to watch it several time over to try and get it right in my head!

Great explanation. I've never even seen a V-G diagram before, so this was all new material for me. I wish you could have shown us a modified V-G diagram showing the unloaded state for comparison. My only complaint (albeit a minor one.)