Opinion on Seneca I

Pilot_DAR good point. All these old airframes, although Piper usually did a good job on corrosion proofing, may have a fatal corrosion area which is impossible to rectify. Am I correct that taking up the carpet allows you to check the carry through area?

I sometimes think the longevity of tube and fabric design is there endless repairability.

Is there no certifiable means of manufacturing that plate?

One would need Piper’s design data, or generate some (DER, in the FAA system, EASA 21 in the EASA system).

Presumably it is uneconomical.

I did fabricate and approve replacement parts for the Seneca. Piper offered a couple of hints, which enabled the task. But, in my opinion, the repair was only worth it, because the new owner of the plane had already spent quite a lot on it. A more effective corrosion inspection before hand would probably have resulted in a different outcome. An under the carpet inspection is a good idea, but may be only be a fraction of the inspection required to assure airworthiness. In fairness to Cessna and Piper, as well as the other prolific manufacturers of the time, they stamped out decent aircraft for their intended role, bu never expected them to last this long, and did not plan nor describe effective detailed inspections for their aging aircraft. Now Cessna has with their SIDs, people are expressing worry. I’ve been working on single Cessnas for forty years, and hold the opinion that the SIDs are a very effective tool to assure continued airworthiness.

Though I really appreciate old airplanes, you cannot just assume that the old plane is the deal of a lifetime because it’s old. It may be a restoration project of lifetime – which is not a problem, if that’s what you’re planning, and you know what you’re getting into. I just bought a 1959 172 to restore. Aside from damaged mag leads, it was in condition good enough for me to fly home. I fully expect to spend three times what I paid for it, on top of the purchase price. But I know I’ll have an aircraft out the other end, which has value exceeding my investment.

I loved the Cessna 310 I used to fly, but they, as most 300 and 400 series Cessnas seem to be a fond memory from the past. In most cases, they are just not worth the cost to inspect them back to airworthiness. They were never designed to last forever, and they were not designed to easily enable the very intrusive inspections required to assure their long term airworthiness.

You really have to know your plane if you’re going to buy very old complex ones…

Have flown Seneca I and II. Don’t really like them.
I like the Aztec though. Seems like you can get one cheap:
http://www.euroga.org/forums/flying/7057-aztec-price-reduced-from-75k-down-to-19k

Pilot_DAR wrote:

You really have to know your plane if you’re going to buy very old complex ones…

Well, very old complex aircraft com in two flavors: already restored or in various steps towards fully restauration. The right plane for the pilot is a key question: Does the fun in flying start with the starter key or the Allen key?

Old (complex) aircraft can be a huge bargain, provided you seek a project. Many of those planes provide much occupation during winter and can be kept flying for the most parts during restoration and they evolve to the aircraft you really like and know by heart. Not a bad investment, if the owner is up to it.

If the owner just seeks utility value… well, that’s what new SR22s and already restored complex aircraft are for.

I’ve flown both the Seneca I and II/III. The I is the original 2×200 hp version without turbos, so it is massively less capable than the II and III. Top speed of the I is around 160 kts, with 155 kts @ 18 GPH total is about the normal planning speed. Range is massively less than the Seneca II/III as the I only has 93 USG fuel tanks, it does not have extended range tanks of 123 USG like the II and III. The lack of turbos will limit it in terms of ceiling as well, I’d think the Seneca 1 will have a service ceiling of about 17000 ft (both engines) and about 4000 ft (OEI). That is massively different from the turbo versions, which can stay at more than 15000 ft OEI.

Most of the remaining Seneca I’s have an MTOW of 1910 kgs, so well below Eurocontrol hassles. With an average of around 1350 kgs empty, the Seneca I can carry around 300 kgs with full fuel and has a total payload of 560 kgs, which is fine for 4 people in some comfort.

Range: The Seneca I is a 500-600 NM range airplane in the best of cases. For Europe, this is mostly sufficient, but it is good not to forget that range wise the Seneca I is a two enigned Arrow I or II.

That said, the Seneca I is very friendly to fly, it is a bit less responsive if you know the II.

Some Seneca I’s are equipped with Rajay Turbos, though I believe the one you are looking at is not.

Maintenance wise, it has already been said that getting parts can be tricky. You know the saga of MFGZ’s Seneca and it’s fuel tanks… this is of course as true if not more for the Seneca I. However, the engines and most equipment are bog standard and it lacks the expensive turbos to service and update. A Seneca I will probably have higher chances to reach TBO on it’s engines and beyond as a turbocharged one.

The airplane I think you are thinking of has been in Switzerland since new to my knowledge, or if not new, then for a very long time. This should make for a pretty good maintenance record, knowing how goldplated oversight in this country is. I am not sure if I remember correctly, but if I do she was pretty well equipped early on with a Sandel and I also think she has radar, which is very good for our area.

You’d have to fly her certainly to see if you can do with the lack of performance vs the II, which you know, and you’d have to talk to the seller and look through the books and bookkeeping in order to get an idea what you are in for. I also don’t know if she is operated under commercial license or not, which would make a difference towards TBO’s e.t.c. From the fact that she has no turbos and the very standard engines and props, she is probably one of the less expensive twins to operate.

As I told you before, if you want me to help looking at it, you know where to find me :)

Useful load on the last Seneca V is quite a lowish 1250-1300 lbs, or 900 lbs with the 1999kg STC, in effect a skinny pilot and a toothbrush if full fuel. You are probably self insuring if you fly at 4750 lbs and have the 1999 kg STC.

The Seneca 1 if not overloaded with extras should have a useful load of 1550 – 1600 lbs, and as Vladimir points out, with a lower fuel burn is a two hour plus VFR reserves six person aircraft. You basically fill to wet bottoms which is around 50 USG. My arithmetic suggests full fuel reduces payload to five pax (including pilot) plus luggage.

With a MAUM of 500 lbs less than the latest version it is a lot easier on the Arrow type undercarriage.

155KTAS sounds generous, assume 145KTAS at 18 USGPH.

Not sure there is anything else out there which can shift 5 people and baggage over 500NM with good reserves for the typical value they command. (Well yes the Cherokee Six).

Hello Vladimir,

Vladimir wrote:

This is only partially true because the extended range tanks on the Seneca II are completely useless unless you fly by yourself after a two month diet. So they are more weight than anything useful. Also the Seneca II uses 24GPH, so practical range would probably even be better on the I.

The Seneca II I used to fly had the 123 USG tanks. Of course the problem with it is, that most of them are down to 1999 kg and that is what makes them less capable, however not as bad as you say here. Maybe the one you fly is massively heavier empty?

Figures I have are as follows from the planes I have in my database:

Seneca II
Empty 1350 kg, Eurocontrol MTOW, 1999 kg, Payload 649 kg, full fuel, 335 kg, usefull load full tanks 314 kg.

Seneca I:
Empty 1343kg, MTOW (Structural) 1905 kg, Payload 562 kg, full fuel 253 kg, usefull load full tanks 309 kg.

So both of them were essentially the same in payload, but of course the 2 has a “real” MTOW of 2072 kg, which would add one full person… ok, not me but definitly you

Performance:

The Seneca II figures I have show it at 75% at 22GPH and 175 kt, 65% at 20GPH and 165kt and 55% at 17 GPH and 155kt. So the performance on long range cruise is comparable (17/155 kt) but of course most fly it at 75 or 65 %.

For range, I’d take 20 USG as final reserve (about 50’) and about 20 USG (and 40 NM) for climb fuel, remains 83 USG for cruise and alternate. With 55% this amounts to 4-50 flight time, which translates into 760 NM plus the climb distance, so 800 NM. With 65% you’d be able to fly 4 hours, which translates into 680NM plus climb, so around 720 NM. High speed cruise of 75% will get you 3:45 hrs, 660 NM plus climb, so around 700 NM.

The Seneca I figures I have show it at 75% with 20.6 GPH and 164 kt, at 65% with 18.3 GPH and 155 kt and at 55% with 16 GPH and 144 kt.

To have a 45 min final reserve will use about 15 USG and will burn approximately 15 USG to cruise level and use again around 40 NM in cruise climb. So of the 93 USG available, 63 remain for cruise and alternate. At 55% that is 4 hrs @ 144 kt, so 560 NM plus climb, around 600 NM total (including alternate). At 65%, that is 3:20 hrs at 155 kt, which gives 533 NM plus climb, so around 570 NM. At 75% you get 3 hours, so a flat 500 NM plus climb, so 540 NM.

Now, this is a rough estimate just for comparison, in general the Seneca I range is about 150 NM shorter than the Seneca II.

Vladimir wrote:

This is a main performance problem I see. The one I am looking at has an additional aerodynamics pack which gives it around 5000-6000ft with OEI, which is still low.

Yes and no. For flying over flat terrain such as north of here, Germany, e.t.c, the OEI ceiling is not so limiting. What it doesn’t give you is the capability to fly IMC over the Alps and have a terrain clearance OEI, but in any case if you are above the MEA on an airway, it will take some time to drift down to MEA and below. It still beats a single in terms of safety. Where the Seneca I, like most twins, is not great is if an engine quits in initial climb.But that is a problem it shares with almost all light twins.

Vladimir wrote:

I have the feeling the the Seneca I is less of a plane in general but more of a plane per dollar.

With this particular one, I agree with you fully. It will make you a nice personal transport on short and mid range if you can live with the limitations it has. My trips with the Seneca 1 have all been to the South of France and were very nice indeed and without any problems.

Nice talking to you right now, with the background you gave me I feel even better about this particular plane.