Should you pull through P&W Wasp Junior Engines before engine start?

[Centaurus]

Query on Pratt & Whitney Wasp Junior 985 radial engines as fitted to the Beaver and the RAAF CAC Winjeel trainer.
Is there a technical requirement to ensure the propeller is pulled through several revolutions prior to starting the engine? Although pulling through certain radial engines before start to ensure no hydraulic lock, has been a feature for many decades (Convair 440, DC3 come to mind) I vaguely recall a warning against this practice based on the fact the fulcrum arm caused by someone heaving on a prop blade against a hydraulic lock has sufficient power to bend a con-rod or otherwise cause internal damage.

On the other hand the starter motor clutch has slippage so that if it encounters a hydraulic lock as it tries to rotate the engine the clutch simply slips beyond a certain torque and so prevents possible internal damage to the engine. On that basis a manual pulling through of the engine is unnecessary and potentially damaging to engine components.

The info I need is specific to the P&W Wasp Junior 985 radial engine. Appreciate facts and any website link that is reliable info.

[camlobe]

Hello Centaurus.
Don't know if it is any help, but here goes.

About 100 years ago when I got into this game (well, it seems that long some times), I was told/taught a thousand things, most not written down.

One of those things regarded radials. Being as radials have some cylinders that are discriminated against by gravity, it is of the utmost importance to ensure that you turn through a number of blades. On those installations that can't be reached due to elevation, then you must turn through on the starter.

I have seen the RNHF remove the lower plugs before putting the Swordfish to bed. I have turned nine blades on the starter on a DC6 before priming and ignition. I have walked through 9 blades on DC3's. So far, I haven't played with single row P&W's, and therefore can not advise specifically.

Perhaps an e-mail to some of the floatplane operators in the USA or Canada might solicit a benificial response.

camlobe

[stevef]

I've spent a fair few years working around radial engines. As you know, it was standard practice on the DC3 and An2 to check for hydraulic locks by turning the engine in its normal direction of rotation. On the DC6, the starter motor clutch saved our muscles. I've never touched a 985 so I'm no help at all. All the 'old school' mechs had the instinct of a light touch when turning the 'round engine' props in case of causing the con rod damage you mentioned. Anyway, this link: http://www.practicalmachinist.com/ubb/ultimatebb.php/topic/11/1242.html is interesting, even if no TOs are quoted. The comment by shapeaholic towards the bottom of the page is noteworthy. Some great photographs of your namesake in there too. Hope you get some more positive feedback.

[NG_Kaptain]

Flew the D18 with 985's, we never pulled our through, but on the C46 and DC6 we used the starter to pull through to check for hydraulic lock. Our manual specifically cautioned us against pulling through by hand on the R2800's.

[ZQA297/30]

NG,
I too flew the D-18S, about 40 years ago. I also remember someone wrecking 2 R985s by cranking them over with ign on, after a long shutdown. (N5883C)
As to whether to hand pull, or crank on starter, my memory may be clouded by some years of R2800 operation on CV440s and DC-6Bs. I tend towards crank on starter, but not positive due to passage of 40 yrs.

[barit1]

We ALWAYS pulled through the R-985 - four blades at least. I'd do this with any radial. I recall encountering hydraulic lock at least once or twice in a couple hundred cold starts.
(I've also hand-propped a 985, not particularly difficult since it's a low compression engine. And I have a video of my dad propping one at age 75!)

[Tee Emm]

And I have a video of my dad propping one at age 75!)

Bloody hell! Ihave enough trouble hand propping a Tiger Moth due vertically challenged. Did your dad get to 76 OK?

[barit1]

Dad maintained his Class 3 physical to age 90; we went for a short local flight on his 90th birthday, and he was PIC since my medical was expired.

He had been known to practice solo touch-&-goes in a T-craft after that (but don't tell the FAA!) :O

[Centaurus]

Thank you all for the replies which have proved invaluable. The link on the Machinists website was stunning especially the photo of the internal workings of the Centaurus engine. I once flew a Sea Fury hence the user name!! It just goes to prove that there are so many varied opinions on engine handling and it is sometimes time consuming to find the facts from the engine manufacturer. Thanks a million again.:ok:

[barit1]

On a geriatric engine type (albeit a very fine type!) I'd be inclined to trust the guy with decades of field experience, and look with some skepticism at the johnny-come-lately publications of a company which hasn't built one in a half-century. Consider for a moment that most of the product support people at P&WC were not yet born when the last Wasp Junior was shipped. :eek:

That said, if someone were to prove me wrong, I would gladly recant and express pleasant surprise!

[stevef]

Aye, true: I learned a lot from the old ex-East African Airways guys when I cut my teeth on the DC3 (Dak/C47, whatever) more years ago than I like to think back. One thing I found alarming during my 15 year association with radials was the misconception by some young pilots that turning the prop backwards relieved a liquid lock... Also that it took more than three blades to check all the cylinders. As most of us know, it was nine blades because of the 16:9 reduction gearing. Happy days, the Dak is still my favourite aircraft. I was also quite fond of the metricated Wright Cyclone (Asz 621R) fitted to the An2. Ah, the sound of inertia starters...

[Centaurus]

I experienced three engine failures on the Convair 440 - never a problem with several years flying the Dakota. But many failures (usually blow backs on take off) with the Rolls Royce Merlins during the five years I operated those engines.

With the radials it was the generally accepted rule (you did what you were told) that the props had to be pulled through before start. The Convair needed three men and a dog to push the prop blades and I wonder now what damage may have been caused although I don't recall ever experiencing a hydraulic lock. It does bring up a question though. If you encounter a hydraulic lock, does that mean manual labour will not "break" the lock in a similar manner that the starter clutch will slip when the engine has a hydraulic lock? As a young pilot my knowledge was was lacking in those far off days especially as the internet had yet to be invented.

[pigboat]

I've flown the R985 on the Beaver and the L10 and L12 and, and the R1340 on the Otter, and never heard of pulling the props through on either type. That being said, I always pulled the prop through manually in the cold, just to limber the engine up a bit to make it easier on the starter. I've never experienced hydraulic lock, but I do remember you were supposed to remove a bottom spark plug to release the accumulated oil if we did experience it. That made it a maintenance problem. :O :E

As far as cranking them over with the ignition on, that was a distinct no-no.

[paco]

I also have flown the Beaver (in the British Army), and it wasn't in their Pilot's Notes (flight manual) as I recall. Adding petrol to the engine oil when it's cold was, which indicates that they did their research.

I agree with barit1, howeer - trust the guy with decades of experience!

Phil

[Lupus-Zorro]

Simple answer is! NO NO NO NO NEVER EVER. The starter has a clutch much weaker than your arms.

[barit1]

Simple answer is! NO NO NO NO NEVER EVER. The starter has a clutch much weaker than your arms.

That's a simplistic answer that overlooks the rather large rotational inertial of the prop (the HS 2D30 weighs about 160#) - A healthy battery & starter will turn this to 200 rpm within one or two blades, and even if the starter clutch yields, all that rotating momentum could easily bend the #5 or #6 connecting rod when the fourth blade passes.

I'd much rather turn it slowly by hand - you can feel the abnormal compression well before anything breaks or bends! :8

[stevef]

I'm with barit1 completely. Only a complete goon would hang off the end of a prop when resistance is felt to hand rotation.

[con-pilot]

I'm with barit1 completely. Only a complete goon would hang off the end of a prop when resistance is felt to hand rotation.

Ah, you never met my ground crew of old did you? :p

[mutley320]

Centaurus,
It's about the Wasps big brother but it's a good read.

"R 4360 Pratt & Whitneys Major Miracle" by Graham White.

Got it from www.amazon.com (http://www.amazon.com) (the american site)

Everyone seems to have their own opinion on this one. Flown Stearmans,Tiger Moths (inverted engine) and i always pull them through first. (no starter on tiger anyway)
Happy flying, would love a go in a DH Beaver.

[Ag2A320]

Gentlemen,
Have used both methods its not a hard fast rule, operated 985's, R1300 /1340's, R-1820/30's & R-2800's sometimes i pulled em through by hand if i could reach the blades or had a ground crew available other times used the starter and listened for clutch slippage, never bent a con-rod on any of the aircraft in over 6000hrs of round engine ops, was taught by my dad who in 18,000hrs of radial ops;who had many failures but none attributed to bent Con-rods/ hydraulic lock.

Eventually modified(Darton Inc. had a similar kit for T-28's,think they called it the "Clean Kit") most of our 1820 powered S-2R Thrush fleet with a B-17 unfeathering pump and plumbed the rocker boxes of the lower cylinders and oil sump to return to the Oil tank:-

Before start up open the Fuel/Oil shut-off valve, hit the pre-oil pump wait til 70 psi in the gauge, engage the starter count 9 blades, place mixture in Auto-Lean (Not Idle Cut-off as the book says found that doing so one does not need to blip the primer switch as A/L provides adequate FF while the engine warms up), Prime till u hear fuel running out the supercharger drain ,engage the starter again mags on at the 2nd blade usually it caught on the 3rd blade, and now wait for 10mins while the engine warmed up or the CHT shows approx 150C, a bit messy as all the excess oil went out the exhaust, added a flame /oil deflector to the exhaust outlet to cut the mess, Occasionally if had time i'd pull the blades through by hand and pull the chip detector bung in the sump and let the oil drain, just as effective as pulling the lower plugs,nowhere as messy: only one drain point, must say in the last 5 years of heavy round engine ops i just used the starter bumping method with no ill effects; good overhauls, burned little oil and very few oil leaks, if after inactive for days very little oil pooled in the lower cylinders or exhaust.

The 1820 & 1830 are the largest i have pulled through by hand myself, the worst prop to work with is the 43E50 prop blades abit short and thin, not like the 23E50 or 33E50. Worked overhauling recips and turbines engines for awhile, both engines types need a gentle touch (a dark art which some of our compatriots have failed to master) both in the cockpit and on the ground.

Had an overhaul shop (Avon Park ,FL) claim a 1820 engine we bought from them which subsequently blew up at 3.5 hrs TTSMOH was due to the fact i had pulled the prop through and bent a conrod, plus his warranty was voided as we were running Mo-gas in the 1820, listened to him profess my short comings as an A&P/IA, and that his engines perform flawlessly, shut him up with one simple question: So who in your shop dropped the # 3 cylinder on its base and then hammered out the damage and fitted it back on my engine?, because the skirt cracked and pieces FOD'ed the engine.

In hindsight ,their bad rep was known by most operators, but it was a package deal a customer traded up to a turbine Thrush, figured it was a good trade cash plus his airframe with a fresh engine overhaul, figured they couldn't screw it up as it was a warranty repair, should have listened to my oldman, he said of that shop if "its anything larger than a 985 dont use em or buy any aircraft fitted with their engines cause the engine will only be good for a boat anchor!", how true,found a much better ovh shop, who didn't mind which method i use to check the engine for hyd-lock and never had such shoddy inspectors.

Try fitting the Oil return kit to the 985's it cuts down the hassle, it was a factory option on the 1965 Beech H-18, well thats the drawings & installation i copied to get 337's on some of the Beech 18's we operated. The S-2R's were in the restricted 137 category, my FSDO guys used to let me fit almost anything on a Field Approval.

On a side note, on the 1340 & 1820 was getting between 3000-4000 hrs on the bottom end between overhauls (on condition TBO; plus wouldn't pull the engine until oil consumption in excess of 3gal/hr or loss of more the 10psi of oil pressure in the zero g portion of the spray run which indicated wear of the main bearing), changed cylinders every 300-600 hrs or so, got a 337 to put the R1820 -76 cyl heavy duty 1425HP cylinders from the Sikorsky CH-34, the MTBf went up to 1000-1600 hrs before having to pull a cylinder.

Ag-Pilot Magazine :Sep 1993 or abouts had a article written by Cal Butler and Greg Levya detailing most aspects of round engine ops in detail and touched on the 985 and 1340 was well, both gentlemen have in excess of 28000 hrs operating round engines in the harsh Ag-conditions and it was more of a tutorial to new round engine pilots and answered most of the myths and questions. Graham White's site is pretty useful its linked here at http://www.enginehistory.org

Have gone all turbine sold most of the round engine aircrafts but still have a 1820 Thrush:- its the second to last built by the factory in 1990,can't bear to part with it, keep it in flyable storage, pull it outside 3-4 times a year and fly it for a couple hours, still only burning 3 qts/hr @ 950hrs TTSMOH and has yet to hydraulic lock even after periods of 3-5 months of inactivity, ground run for 25 mins, then do a power assurance check before doing a full power take-off pulling 43HG and 2500Rpm@126 gals/hr; try to fly it as much as schedule permits; its a guilty pleasure that my accountant and ops manager are beginning to grow tired of ;they keep saying why don't we convert it to a PT-6 or -331 and we could use it daily along with the others instead of being your glorified Hanger Queen, i wont just yet and will continue to hold them at bay, if comes to it i may concede and pull the 1820 and hang the Pt-6 ,prop & mount i have sitting in storage.

Av-gas in our part of the world is at $4.25 a gallon, and we quit using mo-gas as the lead quantity has dropped off, after 28 yrs of running mogas it started messing with the diaphragms in the PD-12 Carb, as well as CHTs and EGTs with occassional missing/backfiring of the engine at power settings above 35 hg, tested with fresh Ovh carbs from Precision and other reputable outfits no cure, switching to Av-gas sorted it out, however the Low lead content of Avgas still is a factor. Maybe someone will come up with an Ethanol conversion for Round engines, cause the only reason we went turbine was the cost of fuel - Jet A @ 1.95,Avgas 4.25 do the math - 5000 gals avgas lasted a month where now 8000 gals of jet a which last about 21/2 months, Ok i'll be the first admit the turbines are nice, but they cant replace the glorious smell of burnt oil and deep rumble of a radial, which even after shut down still talks to you with the pings and creaks of the engine cooling down.

[stevef]

'...but it cant replace the glorious smell of burnt oil and deep rumble of a radial, which even after shut down still talks to you with the pings and creaks of the engine cooling down.'

Aw, man, I love that. Those few words took me right back to the days when I enjoyed aviation. Excellent post.

[xsbank]

I have about 2500 hours 985s and 1340s and we never pulled the props through.

800 hours 1830s on a Dak - always pulled 'em through.

1200 hours 1820 on Trackers (Firecats) never pulled them through.

Never flew the DC-6 but was around them LOTS and they never pulled them through.

Now, counting blades on the starter before ignition, another story. Always.

[barit1]

The Warbirds organization have put together this report (http://www.enginehistory.org/wbn/WBN01.pdf)on the subject. :cool: